doc: enable mathjax support for sphinx documentation

[vis.git] / view.c

#include <string.h>
#include <stdlib.h>
#include <wchar.h>
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include "view.h"
#include "text.h"
#include "text-motions.h"
#include "text-util.h"
#include "util.h"

typedef struct {
        char *symbol;
} SyntaxSymbol;

enum {
        SYNTAX_SYMBOL_SPACE,
        SYNTAX_SYMBOL_TAB,
        SYNTAX_SYMBOL_TAB_FILL,
        SYNTAX_SYMBOL_EOL,
        SYNTAX_SYMBOL_LAST,
};

/* A selection is made up of two marks named cursor and anchor.
 * While the anchor remains fixed the cursor mark follows cursor motions.
 * For a selection (indicated by []), the marks (^) are placed as follows:
 *
 *     [some text]              [!]
 *      ^       ^                ^
 *                               ^
 *
 * That is the marks point to the *start* of the first and last character
 * of the selection. In particular for a single character selection (as
 * depicted on the right above) both marks point to the same location.
 *
 * The view_selections_{get,set} functions take care of adding/removing
 * the necessary offset for the last character.
 */

typedef struct {
        Mark anchor;
        Mark cursor;
} SelectionRegion;

struct Cursor {             /* cursor position */
        Mark cursor;        /* other selection endpoint where it changes */
        Mark anchor;        /* position where the selection was created */
        bool anchored;      /* whether anchor remains fixed */
        size_t pos;         /* in bytes from the start of the file */
        int row, col;       /* in terms of zero based screen coordinates */
        int lastcol;        /* remembered column used when moving across lines */
        Line *line;         /* screen line on which cursor currently resides */
        int generation;     /* used to filter out newly created cursors during iteration */
        int number;         /* how many cursors are located before this one */
        SelectionRegion region; /* saved selection region */
        View *view;         /* associated view to which this cursor belongs */
        Cursor *prev, *next;/* previous/next cursors ordered by location at creation time */
};

/* Viewable area, showing part of a file. Keeps track of cursors and selections.
 * At all times there exists at least one cursor, which is placed in the visible viewport.
 * Additional cursors can be created and positioned anywhere in the file. */
struct View {
        Text *text;         /* underlying text management */
        UiWin *ui;
        Cell cell_blank;    /* used for empty/blank cells */
        int width, height;  /* size of display area */
        size_t start, end;  /* currently displayed area [start, end] in bytes from the start of the file */
        size_t start_last;  /* previously used start of visible area, used to update the mark */
        Mark start_mark;    /* mark to keep track of the start of the visible area */
        size_t lines_size;  /* number of allocated bytes for lines (grows only) */
        Line *lines;        /* view->height number of lines representing view content */
        Line *topline;      /* top of the view, first line currently shown */
        Line *lastline;     /* last currently used line, always <= bottomline */
        Line *bottomline;   /* bottom of view, might be unused if lastline < bottomline */
        Cursor *cursor;     /* main cursor, always placed within the visible viewport */
        Cursor *cursor_latest; /* most recently created cursor */
        Cursor *cursor_dead;/* main cursor which was disposed, will be removed when another cursor is created */
        int cursor_count;   /* how many cursors do currently exist */
        Line *line;         /* used while drawing view content, line where next char will be drawn */
        int col;            /* used while drawing view content, column where next char will be drawn */
        const SyntaxSymbol *symbols[SYNTAX_SYMBOL_LAST]; /* symbols to use for white spaces etc */
        int tabwidth;       /* how many spaces should be used to display a tab character */
        Cursor *cursors;    /* all cursors currently active */
        int cursor_generation; /* used to filter out newly created cursors during iteration */
        bool need_update;   /* whether view has been redrawn */
        bool large_file;    /* optimize for displaying large files */
        int colorcolumn;
};

static const SyntaxSymbol symbols_none[] = {
        [SYNTAX_SYMBOL_SPACE]    = { " " },
        [SYNTAX_SYMBOL_TAB]      = { " " },
        [SYNTAX_SYMBOL_TAB_FILL] = { " " },
        [SYNTAX_SYMBOL_EOL]      = { " " },
};

static const SyntaxSymbol symbols_default[] = {
        [SYNTAX_SYMBOL_SPACE]    = { "·" /* Middle Dot U+00B7 */ },
        [SYNTAX_SYMBOL_TAB]      = { "›" /* Single Right-Pointing Angle Quotation Mark U+203A */ },
        [SYNTAX_SYMBOL_TAB_FILL] = { " " },
        [SYNTAX_SYMBOL_EOL]      = { "↵" /* Downwards Arrow with Corner Leftwards U+21B5 */ },
};

static Cell cell_unused;

static void view_clear(View *view);
static bool view_addch(View *view, Cell *cell);
static void view_cursors_free(Cursor *c);
/* set/move current cursor position to a given (line, column) pair */
static size_t cursor_set(Cursor *cursor, Line *line, int col);

void view_tabwidth_set(View *view, int tabwidth) {
        view->tabwidth = tabwidth;
        view_draw(view);
}

/* reset internal view data structures (cell matrix, line offsets etc.) */
static void view_clear(View *view) {
        memset(view->lines, 0, view->lines_size);
        if (view->start != view->start_last) {
                if (view->start == 0)
                        view->start_mark = EMARK;
                else
                        view->start_mark = text_mark_set(view->text, view->start);
        } else {
                size_t start;
                if (view->start_mark == EMARK)
                        start = 0;
                else
                        start = text_mark_get(view->text, view->start_mark);
                if (start != EPOS)
                        view->start = start;
        }

        view->start_last = view->start;
        view->topline = view->lines;
        view->topline->lineno = view->large_file ? 1 : text_lineno_by_pos(view->text, view->start);
        view->lastline = view->topline;

        size_t line_size = sizeof(Line) + view->width*sizeof(Cell);
        size_t end = view->height * line_size;
        Line *prev = NULL;
        for (size_t i = 0; i < end; i += line_size) {
                Line *line = (Line*)(((char*)view->lines) + i);
                line->prev = prev;
                if (prev)
                        prev->next = line;
                prev = line;
        }
        view->bottomline = prev ? prev : view->topline;
        view->bottomline->next = NULL;
        view->line = view->topline;
        view->col = 0;
        if (view->ui)
                view->cell_blank.style = view->ui->style_get(view->ui, UI_STYLE_DEFAULT);
}

Filerange view_viewport_get(View *view) {
        return (Filerange){ .start = view->start, .end = view->end };
}

/* try to add another character to the view, return whether there was space left */
static bool view_addch(View *view, Cell *cell) {
        if (!view->line)
                return false;

        int width;
        size_t lineno = view->line->lineno;
        unsigned char ch = (unsigned char)cell->data[0];
        cell->style = view->cell_blank.style;

        switch (ch) {
        case '\t':
                cell->width = 1;
                width = view->tabwidth - (view->col % view->tabwidth);
                for (int w = 0; w < width; w++) {
                        if (view->col + 1 > view->width) {
                                view->line = view->line->next;
                                view->col = 0;
                                if (!view->line)
                                        return false;
                                view->line->lineno = lineno;
                        }

                        cell->len = w == 0 ? 1 : 0;
                        int t = w == 0 ? SYNTAX_SYMBOL_TAB : SYNTAX_SYMBOL_TAB_FILL;
                        strncpy(cell->data, view->symbols[t]->symbol, sizeof(cell->data)-1);
                        view->line->cells[view->col] = *cell;
                        view->line->len += cell->len;
                        view->line->width += cell->width;
                        view->col++;
                }
                cell->len = 1;
                return true;
        case '\n':
                cell->width = 1;
                if (view->col + cell->width > view->width) {
                        view->line = view->line->next;
                        view->col = 0;
                        if (!view->line)
                                return false;
                        view->line->lineno = lineno;
                }

                strncpy(cell->data, view->symbols[SYNTAX_SYMBOL_EOL]->symbol, sizeof(cell->data)-1);

                view->line->cells[view->col] = *cell;
                view->line->len += cell->len;
                view->line->width += cell->width;
                for (int i = view->col + 1; i < view->width; i++)
                        view->line->cells[i] = view->cell_blank;

                view->line = view->line->next;
                if (view->line)
                        view->line->lineno = lineno + 1;
                view->col = 0;
                return true;
        default:
                if (ch < 128 && !isprint(ch)) {
                        /* non-printable ascii char, represent it as ^(char + 64) */
                        *cell = (Cell) {
                                .data = { '^', ch == 127 ? '?' : ch + 64, '\0' },
                                .len = 1,
                                .width = 2,
                                .style = cell->style,
                        };
                }

                if (ch == ' ') {
                        strncpy(cell->data, view->symbols[SYNTAX_SYMBOL_SPACE]->symbol, sizeof(cell->data)-1);

                }

                if (view->col + cell->width > view->width) {
                        for (int i = view->col; i < view->width; i++)
                                view->line->cells[i] = view->cell_blank;
                        view->line = view->line->next;
                        view->col = 0;
                }

                if (view->line) {
                        view->line->width += cell->width;
                        view->line->len += cell->len;
                        view->line->lineno = lineno;
                        view->line->cells[view->col] = *cell;
                        view->col++;
                        /* set cells of a character which uses multiple columns */
                        for (int i = 1; i < cell->width; i++)
                                view->line->cells[view->col++] = cell_unused;
                        return true;
                }
                return false;
        }
}

static void cursor_to(Cursor *c, size_t pos) {
        Text *txt = c->view->text;
        c->cursor = text_mark_set(txt, pos);
        if (!c->anchored)
                c->anchor = c->cursor;
        if (pos != c->pos)
                c->lastcol = 0;
        c->pos = pos;
        if (!view_coord_get(c->view, pos, &c->line, &c->row, &c->col)) {
                if (c->view->cursor == c) {
                        c->line = c->view->topline;
                        c->row = 0;
                        c->col = 0;
                }
                return;
        }
        // TODO: minimize number of redraws
        view_draw(c->view);
}

bool view_coord_get(View *view, size_t pos, Line **retline, int *retrow, int *retcol) {
        int row = 0, col = 0;
        size_t cur = view->start;
        Line *line = view->topline;

        if (pos < view->start || pos > view->end) {
                if (retline) *retline = NULL;
                if (retrow) *retrow = -1;
                if (retcol) *retcol = -1;
                return false;
        }

        while (line && line != view->lastline && cur < pos) {
                if (cur + line->len > pos)
                        break;
                cur += line->len;
                line = line->next;
                row++;
        }

        if (line) {
                int max_col = MIN(view->width, line->width);
                while (cur < pos && col < max_col) {
                        cur += line->cells[col].len;
                        /* skip over columns occupied by the same character */
                        while (++col < max_col && line->cells[col].len == 0);
                }
        } else {
                line = view->bottomline;
                row = view->height - 1;
        }

        if (retline) *retline = line;
        if (retrow) *retrow = row;
        if (retcol) *retcol = col;
        return true;
}

/* move the cursor to the character at pos bytes from the begining of the file.
 * if pos is not in the current viewport, redraw the view to make it visible */
void view_cursor_to(View *view, size_t pos) {
        view_cursors_to(view->cursor, pos);
}

/* redraw the complete with data starting from view->start bytes into the file.
 * stop once the screen is full, update view->end, view->lastline */
void view_draw(View *view) {
        view_clear(view);
        /* read a screenful of text considering each character as 4-byte UTF character*/
        const size_t size = view->width * view->height * 4;
        /* current buffer to work with */
        char text[size+1];
        /* remaining bytes to process in buffer */
        size_t rem = text_bytes_get(view->text, view->start, size, text);
        /* NUL terminate text section */
        text[rem] = '\0';
        /* absolute position of character currently being added to display */
        size_t pos = view->start;
        /* current position into buffer from which to interpret a character */
        char *cur = text;
        /* start from known multibyte state */
        mbstate_t mbstate = { 0 };

        Cell cell = { .data = "", .len = 0, .width = 0, }, prev_cell = cell;

        while (rem > 0) {

                /* current 'parsed' character' */
                wchar_t wchar;

                size_t len = mbrtowc(&wchar, cur, rem, &mbstate);
                if (len == (size_t)-1 && errno == EILSEQ) {
                        /* ok, we encountered an invalid multibyte sequence,
                         * replace it with the Unicode Replacement Character
                         * (FFFD) and skip until the start of the next utf8 char */
                        for (len = 1; rem > len && !ISUTF8(cur[len]); len++);
                        cell = (Cell){ .data = "\xEF\xBF\xBD", .len = len, .width = 1 };
                } else if (len == (size_t)-2) {
                        /* not enough bytes available to convert to a
                         * wide character. advance file position and read
                         * another junk into buffer.
                         */
                        rem = text_bytes_get(view->text, pos, size, text);
                        text[rem] = '\0';
                        cur = text;
                        continue;
                } else if (len == 0) {
                        /* NUL byte encountered, store it and continue */
                        cell = (Cell){ .data = "\x00", .len = 1, .width = 2 };
                } else {
                        if (len >= sizeof(cell.data))
                                len = sizeof(cell.data)-1;
                        for (size_t i = 0; i < len; i++)
                                cell.data[i] = cur[i];
                        cell.data[len] = '\0';
                        cell.len = len;
                        cell.width = wcwidth(wchar);
                        if (cell.width == -1)
                                cell.width = 1;
                }

                if (cell.width == 0 && prev_cell.len + cell.len < sizeof(cell.data)) {
                        prev_cell.len += cell.len;
                        strcat(prev_cell.data, cell.data);
                } else {
                        if (prev_cell.len && !view_addch(view, &prev_cell))
                                break;
                        pos += prev_cell.len;
                        prev_cell = cell;
                }

                rem -= cell.len;
                cur += cell.len;

                memset(&cell, 0, sizeof cell);
        }

        if (prev_cell.len && view_addch(view, &prev_cell))
                pos += prev_cell.len;

        /* set end of viewing region */
        view->end = pos;
        if (view->line) {
                bool eof = view->end == text_size(view->text);
                if (view->line->len == 0 && eof && view->line->prev)
                        view->lastline = view->line->prev;
                else
                        view->lastline = view->line;
        } else {
                view->lastline = view->bottomline;
        }

        /* clear remaining of line, important to show cursor at end of file */
        if (view->line) {
                for (int x = view->col; x < view->width; x++)
                        view->line->cells[x] = view->cell_blank;
        }

        /* resync position of cursors within visible area */
        for (Cursor *c = view->cursors; c; c = c->next) {
                size_t pos = view_cursors_pos(c);
                if (!view_coord_get(view, pos, &c->line, &c->row, &c->col) && 
                    c == view->cursor) {
                        c->line = view->topline;
                        c->row = 0;
                        c->col = 0;
                }
        }

        view->need_update = true;
}

void view_invalidate(View *view) {
        view->need_update = true;
}

bool view_update(View *view) {
        if (!view->need_update)
                return false;
        for (Line *l = view->lastline->next; l; l = l->next) {
                for (int x = 0; x < view->width; x++)
                        l->cells[x] = view->cell_blank;
        }
        view->need_update = false;
        return true;
}

bool view_resize(View *view, int width, int height) {
        if (width <= 0)
                width = 1;
        if (height <= 0)
                height = 1;
        if (view->width == width && view->height == height) {
                view->need_update = true;
                return true;
        }
        size_t lines_size = height*(sizeof(Line) + width*sizeof(Cell));
        if (lines_size > view->lines_size) {
                Line *lines = realloc(view->lines, lines_size);
                if (!lines)
                        return false;
                view->lines = lines;
                view->lines_size = lines_size;
        }
        view->width = width;
        view->height = height;
        memset(view->lines, 0, view->lines_size);
        view_draw(view);
        return true;
}

int view_height_get(View *view) {
        return view->height;
}

int view_width_get(View *view) {
        return view->width;
}

void view_free(View *view) {
        if (!view)
                return;
        while (view->cursors)
                view_cursors_free(view->cursors);
        free(view->lines);
        free(view);
}

void view_reload(View *view, Text *text) {
        view->text = text;
        view_selections_clear(view);
        view_cursor_to(view, 0);
}

View *view_new(Text *text) {
        if (!text)
                return NULL;
        View *view = calloc(1, sizeof(View));
        if (!view)
                return NULL;
        if (!view_cursors_new(view, 0)) {
                view_free(view);
                return NULL;
        }

        view->cell_blank = (Cell) {
                .width = 0,
                .len = 0,
                .data = " ",
        };
        view->text = text;
        view->tabwidth = 8;
        view_options_set(view, 0);

        if (!view_resize(view, 1, 1)) {
                view_free(view);
                return NULL;
        }

        view_cursor_to(view, 0);

        return view;
}

void view_ui(View *view, UiWin* ui) {
        view->ui = ui;
}

static size_t cursor_set(Cursor *cursor, Line *line, int col) {
        int row = 0;
        View *view = cursor->view;
        size_t pos = view->start;
        /* get row number and file offset at start of the given line */
        for (Line *cur = view->topline; cur && cur != line; cur = cur->next) {
                pos += cur->len;
                row++;
        }

        /* for characters which use more than 1 column, make sure we are on the left most */
        while (col > 0 && line->cells[col].len == 0)
                col--;
        /* calculate offset within the line */
        for (int i = 0; i < col; i++)
                pos += line->cells[i].len;

        cursor->col = col;
        cursor->row = row;
        cursor->line = line;

        cursor_to(cursor, pos);

        return pos;
}

bool view_viewport_down(View *view, int n) {
        Line *line;
        if (view->end >= text_size(view->text))
                return false;
        if (n >= view->height) {
                view->start = view->end;
        } else {
                for (line = view->topline; line && n > 0; line = line->next, n--)
                        view->start += line->len;
        }
        view_draw(view);
        return true;
}

bool view_viewport_up(View *view, int n) {
        /* scrolling up is somewhat tricky because we do not yet know where
         * the lines start, therefore scan backwards but stop at a reasonable
         * maximum in case we are dealing with a file without any newlines
         */
        if (view->start == 0)
                return false;
        size_t max = view->width * view->height;
        char c;
        Iterator it = text_iterator_get(view->text, view->start - 1);

        if (!text_iterator_byte_get(&it, &c))
                return false;
        size_t off = 0;
        /* skip newlines immediately before display area */
        if (c == '\n' && text_iterator_byte_prev(&it, &c))
                off++;
        do {
                if (c == '\n' && --n == 0)
                        break;
                if (++off > max)
                        break;
        } while (text_iterator_byte_prev(&it, &c));
        view->start -= MIN(view->start, off);
        view_draw(view);
        return true;
}

void view_redraw_top(View *view) {
        Line *line = view->cursor->line;
        for (Line *cur = view->topline; cur && cur != line; cur = cur->next)
                view->start += cur->len;
        view_draw(view);
        view_cursor_to(view, view->cursor->pos);
}

void view_redraw_center(View *view) {
        int center = view->height / 2;
        size_t pos = view->cursor->pos;
        for (int i = 0; i < 2; i++) {
                int linenr = 0;
                Line *line = view->cursor->line;
                for (Line *cur = view->topline; cur && cur != line; cur = cur->next)
                        linenr++;
                if (linenr < center) {
                        view_slide_down(view, center - linenr);
                        continue;
                }
                for (Line *cur = view->topline; cur && cur != line && linenr > center; cur = cur->next) {
                        view->start += cur->len;
                        linenr--;
                }
                break;
        }
        view_draw(view);
        view_cursor_to(view, pos);
}

void view_redraw_bottom(View *view) {
        Line *line = view->cursor->line;
        if (line == view->lastline)
                return;
        size_t pos = view->cursor->pos;
        view_viewport_up(view, view->height);
        while (pos >= view->end && view_viewport_down(view, 1));
        cursor_to(view->cursor, pos);
}

size_t view_slide_up(View *view, int lines) {
        Cursor *cursor = view->cursor;
        if (view_viewport_down(view, lines)) {
                if (cursor->line == view->topline)
                        cursor_set(cursor, view->topline, cursor->col);
                else
                        view_cursor_to(view, cursor->pos);
        } else {
                view_screenline_down(cursor);
        }
        return cursor->pos;
}

size_t view_slide_down(View *view, int lines) {
        Cursor *cursor = view->cursor;
        bool lastline = cursor->line == view->lastline;
        size_t col = cursor->col;
        if (view_viewport_up(view, lines)) {
                if (lastline)
                        cursor_set(cursor, view->lastline, col);
                else
                        view_cursor_to(view, cursor->pos);
        } else {
                view_screenline_up(cursor);
        }
        return cursor->pos;
}

size_t view_scroll_up(View *view, int lines) {
        Cursor *cursor = view->cursor;
        if (view_viewport_up(view, lines)) {
                Line *line = cursor->line < view->lastline ? cursor->line : view->lastline;
                cursor_set(cursor, line, view->cursor->col);
        } else {
                view_cursor_to(view, 0);
        }
        return cursor->pos;
}

size_t view_scroll_page_up(View *view) {
        Cursor *cursor = view->cursor;
        if (view->start == 0) {
                view_cursor_to(view, 0);
        } else {
                view_cursor_to(view, view->start-1);
                view_redraw_bottom(view);
                view_screenline_begin(cursor);
        }
        return cursor->pos;
}

size_t view_scroll_page_down(View *view) {
        view_scroll_down(view, view->height);
        return view_screenline_begin(view->cursor);
}

size_t view_scroll_halfpage_up(View *view) {
        Cursor *cursor = view->cursor;
        if (view->start == 0) {
                view_cursor_to(view, 0);
        } else {
                view_cursor_to(view, view->start-1);
                view_redraw_center(view);
                view_screenline_begin(cursor);
        }
        return cursor->pos;
}

size_t view_scroll_halfpage_down(View *view) {
        size_t end = view->end;
        size_t pos = view_scroll_down(view, view->height/2);
        if (pos < text_size(view->text))
                view_cursor_to(view, end);
        return view->cursor->pos;
}

size_t view_scroll_down(View *view, int lines) {
        Cursor *cursor = view->cursor;
        if (view_viewport_down(view, lines)) {
                Line *line = cursor->line > view->topline ? cursor->line : view->topline;
                cursor_set(cursor, line, cursor->col);
        } else {
                view_cursor_to(view, text_size(view->text));
        }
        return cursor->pos;
}

size_t view_line_up(Cursor *cursor) {
        View *view = cursor->view;
        int lastcol = cursor->lastcol;
        if (!lastcol)
                lastcol = cursor->col;
        size_t pos = text_line_up(cursor->view->text, cursor->pos);
        bool offscreen = view->cursor == cursor && pos < view->start;
        view_cursors_to(cursor, pos);
        if (offscreen)
                view_redraw_top(view);
        if (cursor->line)
                cursor_set(cursor, cursor->line, lastcol);
        cursor->lastcol = lastcol;
        return cursor->pos;
}

size_t view_line_down(Cursor *cursor) {
        View *view = cursor->view;
        int lastcol = cursor->lastcol;
        if (!lastcol)
                lastcol = cursor->col;
        size_t pos = text_line_down(cursor->view->text, cursor->pos);
        bool offscreen = view->cursor == cursor && pos > view->end;
        view_cursors_to(cursor, pos);
        if (offscreen)
                view_redraw_bottom(view);
        if (cursor->line)
                cursor_set(cursor, cursor->line, lastcol);
        cursor->lastcol = lastcol;
        return cursor->pos;
}

size_t view_screenline_up(Cursor *cursor) {
        if (!cursor->line)
                return view_line_up(cursor);
        int lastcol = cursor->lastcol;
        if (!lastcol)
                lastcol = cursor->col;
        if (!cursor->line->prev)
                view_scroll_up(cursor->view, 1);
        if (cursor->line->prev)
                cursor_set(cursor, cursor->line->prev, lastcol);
        cursor->lastcol = lastcol;
        return cursor->pos;
}

size_t view_screenline_down(Cursor *cursor) {
        if (!cursor->line)
                return view_line_down(cursor);
        int lastcol = cursor->lastcol;
        if (!lastcol)
                lastcol = cursor->col;
        if (!cursor->line->next && cursor->line == cursor->view->bottomline)
                view_scroll_down(cursor->view, 1);
        if (cursor->line->next)
                cursor_set(cursor, cursor->line->next, lastcol);
        cursor->lastcol = lastcol;
        return cursor->pos;
}

size_t view_screenline_begin(Cursor *cursor) {
        if (!cursor->line)
                return cursor->pos;
        return cursor_set(cursor, cursor->line, 0);
}

size_t view_screenline_middle(Cursor *cursor) {
        if (!cursor->line)
                return cursor->pos;
        return cursor_set(cursor, cursor->line, cursor->line->width / 2);
}

size_t view_screenline_end(Cursor *cursor) {
        if (!cursor->line)
                return cursor->pos;
        int col = cursor->line->width - 1;
        return cursor_set(cursor, cursor->line, col >= 0 ? col : 0);
}

size_t view_cursor_get(View *view) {
        return view_cursors_pos(view->cursor);
}

Line *view_lines_first(View *view) {
        return view->topline;
}

Line *view_lines_last(View *view) {
        return view->lastline;
}

Line *view_cursors_line_get(Cursor *c) {
        return c->line;
}

void view_scroll_to(View *view, size_t pos) {
        view_cursors_scroll_to(view->cursor, pos);
}

void view_options_set(View *view, enum UiOption options) {
        const int mapping[] = {
                [SYNTAX_SYMBOL_SPACE]    = UI_OPTION_SYMBOL_SPACE,
                [SYNTAX_SYMBOL_TAB]      = UI_OPTION_SYMBOL_TAB,
                [SYNTAX_SYMBOL_TAB_FILL] = UI_OPTION_SYMBOL_TAB_FILL,
                [SYNTAX_SYMBOL_EOL]      = UI_OPTION_SYMBOL_EOL,
        };

        for (int i = 0; i < LENGTH(mapping); i++) {
                view->symbols[i] = (options & mapping[i]) ? &symbols_default[i] :
                        &symbols_none[i];
        }

        if (options & UI_OPTION_LINE_NUMBERS_ABSOLUTE)
                options &= ~UI_OPTION_LARGE_FILE;

        view->large_file = (options & UI_OPTION_LARGE_FILE);

        if (view->ui)
                view->ui->options_set(view->ui, options);
}

enum UiOption view_options_get(View *view) {
        return view->ui ? view->ui->options_get(view->ui) : 0;
}

void view_colorcolumn_set(View *view, int col) {
        if (col >= 0)
                view->colorcolumn = col;
}

int view_colorcolumn_get(View *view) {
        return view->colorcolumn;
}

size_t view_screenline_goto(View *view, int n) {
        size_t pos = view->start;
        for (Line *line = view->topline; --n > 0 && line != view->lastline; line = line->next)
                pos += line->len;
        return pos;
}

static Cursor *cursors_new(View *view, size_t pos, bool force) {
        Cursor *c = calloc(1, sizeof(*c));
        if (!c)
                return NULL;
        c->view = view;
        c->generation = view->cursor_generation;
        if (!view->cursors) {
                view->cursor = c;
                view->cursor_latest = c;
                view->cursors = c;
                view->cursor_count = 1;
                return c;
        }

        Cursor *prev = NULL, *next = NULL;
        Cursor *latest = view->cursor_latest ? view->cursor_latest : view->cursor;
        size_t cur = view_cursors_pos(latest);
        if (pos == cur) {
                prev = latest;
                next = prev->next;
        } else if (pos > cur) {
                prev = latest;
                for (next = prev->next; next; prev = next, next = next->next) {
                        cur = view_cursors_pos(next);
                        if (pos <= cur)
                                break;
                }
        } else if (pos < cur) {
                next = latest;
                for (prev = next->prev; prev; next = prev, prev = prev->prev) {
                        cur = view_cursors_pos(prev);
                        if (pos >= cur)
                                break;
                }
        }

        if (pos == cur && !force)
                goto err;

        for (Cursor *after = next; after; after = after->next)
                after->number++;

        c->prev = prev;
        c->next = next;
        if (next)
                next->prev = c;
        if (prev) {
                prev->next = c;
                c->number = prev->number + 1;
        } else {
                view->cursors = c;
        }
        view->cursor_latest = c;
        view->cursor_count++;
        view_cursors_dispose(view->cursor_dead);
        view_cursors_to(c, pos);
        return c;
err:
        free(c);
        return NULL;
}

Cursor *view_cursors_new(View *view, size_t pos) {
        return cursors_new(view, pos, false);
}

Cursor *view_cursors_new_force(View *view, size_t pos) {
        return cursors_new(view, pos, true);
}

int view_cursors_count(View *view) {
        return view->cursor_count;
}

int view_cursors_number(Cursor *c) {
        return c->number;
}

int view_cursors_column_count(View *view) {
        Text *txt = view->text;
        int cpl_max = 0, cpl = 0; /* cursors per line */
        size_t line_prev = 0;
        for (Cursor *c = view->cursors; c; c = c->next) {
                size_t pos = view_cursors_pos(c);
                size_t line = text_lineno_by_pos(txt, pos);
                if (line == line_prev)
                        cpl++;
                else
                        cpl = 1;
                line_prev = line;
                if (cpl > cpl_max)
                        cpl_max = cpl;
        }
        return cpl_max;
}

static Cursor *cursors_column_next(View *view, Cursor *c, int column) {
        size_t line_cur = 0;
        int column_cur = 0;
        Text *txt = view->text;
        if (c) {
                size_t pos = view_cursors_pos(c);
                line_cur = text_lineno_by_pos(txt, pos);
                column_cur = INT_MIN;
        } else {
                c = view->cursors;
        }

        for (; c; c = c->next) {
                size_t pos = view_cursors_pos(c);
                size_t line = text_lineno_by_pos(txt, pos);
                if (line != line_cur) {
                        line_cur = line;
                        column_cur = 0;
                } else {
                        column_cur++;
                }
                if (column == column_cur)
                        return c;
        }
        return NULL;
}

Cursor *view_cursors_column(View *view, int column) {
        return cursors_column_next(view, NULL, column);
}

Cursor *view_cursors_column_next(Cursor *c, int column) {
        return cursors_column_next(c->view, c, column);
}

bool view_cursors_multiple(View *view) {
        return view->cursors && view->cursors->next;
}

static void view_cursors_free(Cursor *c) {
        if (!c)
                return;
        for (Cursor *after = c->next; after; after = after->next)
                after->number--;
        if (c->prev)
                c->prev->next = c->next;
        if (c->next)
                c->next->prev = c->prev;
        if (c->view->cursors == c)
                c->view->cursors = c->next;
        if (c->view->cursor == c)
                c->view->cursor = c->next ? c->next : c->prev;
        if (c->view->cursor_dead == c)
                c->view->cursor_dead = NULL;
        if (c->view->cursor_latest == c)
                c->view->cursor_latest = c->prev ? c->prev : c->next;
        c->view->cursor_count--;
        free(c);
}

bool view_cursors_dispose(Cursor *c) {
        if (!c)
                return true;
        View *view = c->view;
        if (!view->cursors || !view->cursors->next)
                return false;
        view_cursors_free(c);
        view_cursors_primary_set(view->cursor);
        return true;
}

bool view_cursors_dispose_force(Cursor *c) {
        if (view_cursors_dispose(c))
                return true;
        View *view = c->view;
        if (view->cursor_dead)
                return false;
        view_cursors_selection_clear(c);
        view->cursor_dead = c;
        return true;
}

Cursor *view_cursor_disposed(View *view) {
        Cursor *c = view->cursor_dead;
        view->cursor_dead = NULL;
        return c;
}

Cursor *view_cursors(View *view) {
        view->cursor_generation++;
        return view->cursors;
}

Cursor *view_cursors_primary_get(View *view) {
        view->cursor_generation++;
        return view->cursor;
}

void view_cursors_primary_set(Cursor *c) {
        if (!c)
                return;
        c->view->cursor = c;
}

Cursor *view_cursors_prev(Cursor *c) {
        View *view = c->view;
        for (c = c->prev; c; c = c->prev) {
                if (c->generation != view->cursor_generation)
                        return c;
        }
        view->cursor_generation++;
        return NULL;
}

Cursor *view_cursors_next(Cursor *c) {
        View *view = c->view;
        for (c = c->next; c; c = c->next) {
                if (c->generation != view->cursor_generation)
                        return c;
        }
        view->cursor_generation++;
        return NULL;
}

size_t view_cursors_pos(Cursor *c) {
        return text_mark_get(c->view->text, c->cursor);
}

size_t view_cursors_line(Cursor *c) {
        size_t pos = view_cursors_pos(c);
        return text_lineno_by_pos(c->view->text, pos);
}

size_t view_cursors_col(Cursor *c) {
        size_t pos = view_cursors_pos(c);
        return text_line_char_get(c->view->text, pos) + 1;
}

int view_cursors_cell_get(Cursor *c) {
        return c->line ? c->col : -1;
}

int view_cursors_cell_set(Cursor *c, int cell) {
        if (!c->line || cell < 0)
                return -1;
        cursor_set(c, c->line, cell);
        return c->col;
}

void view_cursors_scroll_to(Cursor *c, size_t pos) {
        View *view = c->view;
        if (view->cursor == c) {
                view_draw(view);
                while (pos < view->start && view_viewport_up(view, 1));
                while (pos > view->end && view_viewport_down(view, 1));
        }
        view_cursors_to(c, pos);
}

void view_cursors_to(Cursor *c, size_t pos) {
        View *view = c->view;
        if (pos == EPOS)
                return;
        size_t size = text_size(view->text);
        if (pos > size)
                pos = size;
        if (c->view->cursor == c) {
                /* make sure we redraw changes to the very first character of the window */
                if (view->start == pos)
                        view->start_last = 0;

                if (view->end == pos && view->lastline == view->bottomline) {
                        view->start += view->topline->len;
                        view_draw(view);
                }

                if (pos < view->start || pos > view->end) {
                        view->start = pos;
                        view_viewport_up(view, view->height / 2);
                }

                if (pos <= view->start || pos > view->end) {
                        view->start = text_line_begin(view->text, pos);
                        view_draw(view);
                }

                if (pos <= view->start || pos > view->end) {
                        view->start = pos;
                        view_draw(view);
                }
        }

        cursor_to(c, pos);
}

void view_cursors_place(Cursor *c, size_t line, size_t col) {
        Text *txt = c->view->text;
        size_t pos = text_pos_by_lineno(txt, line);
        pos = text_line_char_set(txt, pos, col > 0 ? col-1 : col);
        view_cursors_to(c, pos);
}

void view_cursors_selection_start(Cursor *c) {
        c->anchored = true;
}

void view_cursors_selection_clear(Cursor *c) {
        c->anchored = false;
        c->anchor = c->cursor;
        c->view->need_update = true;
}

void view_cursors_selection_swap(Cursor *s) {
        Mark temp = s->anchor;
        s->anchor = s->cursor;
        s->cursor = temp;
        view_cursors_to(s, text_mark_get(s->view->text, s->cursor));
}

bool view_selection_anchored(Selection *s) {
        return s->anchored;
}

void view_selections_clear(View *view) {
        for (Cursor *c = view->cursors; c; c = c->next)
                view_cursors_selection_clear(c);
        view_draw(view);
}

void view_cursors_clear(View *view) {
        for (Cursor *c = view->cursors, *next; c; c = next) {
                next = c->next;
                if (c != view->cursor)
                        view_cursors_free(c);
        }
        view_draw(view);
}

Filerange view_selection_get(View *view) {
        return view_cursors_selection_get(view->cursor);
}

Filerange view_cursors_selection_get(Selection *s) {
        if (!s)
                return text_range_empty();
        Text *txt = s->view->text;
        size_t anchor = text_mark_get(txt, s->anchor);
        size_t cursor = text_mark_get(txt, s->cursor);
        Filerange sel = text_range_new(anchor, cursor);
        if (text_range_valid(&sel))
                sel.end = text_char_next(txt, sel.end);
        return sel;
}

void view_cursors_selection_set(Selection *s, const Filerange *r) {
        if (!text_range_valid(r))
                return;
        Text *txt = s->view->text;
        size_t anchor = text_mark_get(txt, s->anchor);
        size_t cursor = text_mark_get(txt, s->cursor);
        bool left_extending = anchor != EPOS && anchor > cursor;
        size_t end = r->end;
        if (r->start != end)
                end = text_char_prev(txt, end);
        if (left_extending) {
                s->anchor = text_mark_set(txt, end);
                s->cursor = text_mark_set(txt, r->start);
        } else {
                s->anchor = text_mark_set(txt, r->start);
                s->cursor = text_mark_set(txt, end);
        }
        s->anchored = true;
        view_cursors_to(s, text_mark_get(s->view->text, s->cursor));
}

void view_cursors_selection_save(Selection *s) {
        s->region.cursor = s->cursor;
        s->region.anchor = s->anchor;
}

bool view_cursors_selection_restore(Selection *s) {
        Text *txt = s->view->text;
        size_t pos = text_mark_get(txt, s->region.cursor);
        if (pos == EPOS)
                return false;
        if (s->region.anchor != s->region.cursor && text_mark_get(txt, s->region.anchor) == EPOS)
                return false;
        s->cursor = s->region.cursor;
        s->anchor = s->region.anchor;
        s->anchored = true;
        view_cursors_to(s, pos);
        return true;
}

Text *view_text(View *view) {
        return view->text;
}

bool view_style_define(View *view, enum UiStyle id, const char *style) {
        return view->ui->style_define(view->ui, id, style);
}

void view_style(View *view, enum UiStyle style_id, size_t start, size_t end) {
        if (end < view->start || start > view->end)
                return;

        CellStyle style = view->ui->style_get(view->ui, style_id);
        size_t pos = view->start;
        Line *line = view->topline;

        /* skip lines before range to be styled */
        while (line && pos + line->len <= start) {
                pos += line->len;
                line = line->next;
        }

        if (!line)
                return;

        int col = 0, width = view->width;

        /* skip columns before range to be styled */
        while (pos < start && col < width)
                pos += line->cells[col++].len;

        do {
                while (pos <= end && col < width) {
                        pos += line->cells[col].len;
                        line->cells[col++].style = style;
                }
                col = 0;
        } while (pos <= end && (line = line->next));
}