#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "./editor.h"
#include "./common.h"

void editor_backspace(Editor *e)
{
    if (e->cursor > e->data.count) {
        e->cursor = e->data.count;
    }
    if (e->cursor == 0) return;

    memmove(
        &e->data.items[e->cursor - 1],
        &e->data.items[e->cursor],
        e->data.count - e->cursor
    );
    e->cursor -= 1;
    e->data.count -= 1;
    editor_retokenize(e);
}

void editor_delete(Editor *e)
{
    if (e->cursor >= e->data.count) return;
    memmove(
        &e->data.items[e->cursor],
        &e->data.items[e->cursor + 1],
        e->data.count - e->cursor - 1
    );
    e->data.count -= 1;
    editor_retokenize(e);
}

// TODO: make sure that you always have new line at the end of the file while saving
// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206

Errno editor_save_as(Editor *e, const char *file_path)
{
    printf("Saving as %s...\n", file_path);
    Errno err = write_entire_file(file_path, e->data.items, e->data.count);
    if (err != 0) return err;
    e->file_path.count = 0;
    sb_append_cstr(&e->file_path, file_path);
    sb_append_null(&e->file_path);
    return 0;
}

Errno editor_save(const Editor *e)
{
    assert(e->file_path.count > 0);
    printf("Saving as %s...\n", e->file_path.items);
    return write_entire_file(e->file_path.items, e->data.items, e->data.count);
}

Errno editor_load_from_file(Editor *e, const char *file_path)
{
    printf("Loading %s\n", file_path);

    e->data.count = 0;
    Errno err = read_entire_file(file_path, &e->data);
    if (err != 0) return err;

    e->cursor = 0;

    editor_retokenize(e);

    e->file_path.count = 0;
    sb_append_cstr(&e->file_path, file_path);
    sb_append_null(&e->file_path);

    return 0;
}

size_t editor_cursor_row(const Editor *e)
{
    assert(e->lines.count > 0);
    for (size_t row = 0; row < e->lines.count; ++row) {
        Line line = e->lines.items[row];
        if (line.begin <= e->cursor && e->cursor <= line.end) {
            return row;
        }
    }
    return e->lines.count - 1;
}

void editor_move_line_up(Editor *e)
{
    size_t cursor_row = editor_cursor_row(e);
    size_t cursor_col = e->cursor - e->lines.items[cursor_row].begin;
    if (cursor_row > 0) {
        Line next_line = e->lines.items[cursor_row - 1];
        size_t next_line_size = next_line.end - next_line.begin;
        if (cursor_col > next_line_size) cursor_col = next_line_size;
        e->cursor = next_line.begin + cursor_col;
    }
}

void editor_move_line_down(Editor *e)
{
    size_t cursor_row = editor_cursor_row(e);
    size_t cursor_col = e->cursor - e->lines.items[cursor_row].begin;
    if (cursor_row < e->lines.count - 1) {
        Line next_line = e->lines.items[cursor_row + 1];
        size_t next_line_size = next_line.end - next_line.begin;
        if (cursor_col > next_line_size) cursor_col = next_line_size;
        e->cursor = next_line.begin + cursor_col;
    }
}

void editor_move_char_left(Editor *e)
{
    if (e->cursor > 0) e->cursor -= 1;
}

void editor_move_char_right(Editor *e)
{
    if (e->cursor < e->data.count) e->cursor += 1;
}

void editor_move_word_left(Editor *e)
{
    while (e->cursor > 0 && !isalnum(e->data.items[e->cursor - 1])) {
        e->cursor -= 1;
    }
    while (e->cursor > 0 && isalnum(e->data.items[e->cursor - 1])) {
        e->cursor -= 1;
    }
}

void editor_move_word_right(Editor *e)
{
    while (e->cursor < e->data.count && !isalnum(e->data.items[e->cursor])) {
        e->cursor += 1;
    }
    while (e->cursor < e->data.count && isalnum(e->data.items[e->cursor])) {
        e->cursor += 1;
    }
}

void editor_insert_char(Editor *e, char x)
{
    editor_insert_buf(e, &x, 1);
}

void editor_insert_buf(Editor *e, char *buf, size_t buf_len)
{
    if (e->cursor > e->data.count) {
        e->cursor = e->data.count;
    }

    for (size_t i = 0; i < buf_len; ++i) {
        da_append(&e->data, '\0');
    }
    memmove(
        &e->data.items[e->cursor + buf_len],
        &e->data.items[e->cursor],
        e->data.count - e->cursor - buf_len
    );
    memcpy(&e->data.items[e->cursor], buf, buf_len);
    e->cursor += buf_len;
    editor_retokenize(e);
}

void editor_retokenize(Editor *e)
{
    // Lines
    {
        e->lines.count = 0;

        Line line;
        line.begin = 0;

        for (size_t i = 0; i < e->data.count; ++i) {
            if (e->data.items[i] == '\n') {
                line.end = i;
                da_append(&e->lines, line);
                line.begin = i + 1;
            }
        }

        line.end = e->data.count;
        da_append(&e->lines, line);
    }

    // Syntax Highlighting
    {
        e->tokens.count = 0;
        Lexer l = lexer_new(e->atlas, e->data.items, e->data.count);
        Token t = lexer_next(&l);
        while (t.kind != TOKEN_END) {
            da_append(&e->tokens, t);
            t = lexer_next(&l);
        }
    }
}

bool editor_line_starts_with(Editor *e, size_t row, size_t col, const char *prefix)
{
    size_t prefix_len = strlen(prefix);
    if (prefix_len == 0) {
        return true;
    }
    Line line = e->lines.items[row];
    if (col + prefix_len - 1 >= line.end) {
        return false;
    }
    for (size_t i = 0; i < prefix_len; ++i) {
        if (prefix[i] != e->data.items[line.begin + col + i]) {
            return false;
        }
    }
    return true;
}

const char *editor_line_starts_with_one_of(Editor *e, size_t row, size_t col, const char **prefixes, size_t prefixes_count)
{
    for (size_t i = 0; i < prefixes_count; ++i) {
        if (editor_line_starts_with(e, row, col, prefixes[i])) {
            return prefixes[i];
        }
    }
    return NULL;
}

void editor_render(SDL_Window *window, Free_Glyph_Atlas *atlas, Simple_Renderer *sr, Editor *editor)
{
    int w, h;
    SDL_GetWindowSize(window, &w, &h);

    float max_line_len = 0.0f;

    sr->resolution = vec2f(w, h);
    sr->time = (float) SDL_GetTicks() / 1000.0f;

    // Render selection
    {
        simple_renderer_set_shader(sr, SHADER_FOR_COLOR);
        if (editor->selection) {
            for (size_t row = 0; row < editor->lines.count; ++row) {
                size_t select_begin_chr = editor->select_begin;
                size_t select_end_chr = editor->cursor;
                if (select_begin_chr > select_end_chr) {
                    SWAP(size_t, select_begin_chr, select_end_chr);
                }

                Line line_chr = editor->lines.items[row];

                if (select_begin_chr < line_chr.begin) {
                    select_begin_chr = line_chr.begin;
                }

                if (select_end_chr > line_chr.end) {
                    select_end_chr = line_chr.end;
                }

                if (select_begin_chr <= select_end_chr) {
                    Vec2f select_begin_scr = vec2f(0, -((float)row + CURSOR_OFFSET) * FREE_GLYPH_FONT_SIZE);
                    free_glyph_atlas_measure_line_sized(
                        atlas, editor->data.items + line_chr.begin, select_begin_chr - line_chr.begin,
                        &select_begin_scr);

                    Vec2f select_end_scr = select_begin_scr;
                    free_glyph_atlas_measure_line_sized(
                        atlas, editor->data.items + select_begin_chr, select_end_chr - select_begin_chr,
                        &select_end_scr);

                    Vec4f selection_color = vec4f(.25, .25, .25, 1);
                    simple_renderer_solid_rect(sr, select_begin_scr, vec2f(select_end_scr.x - select_begin_scr.x, FREE_GLYPH_FONT_SIZE), selection_color);
                }
            }
        }
        simple_renderer_flush(sr);
    }

    // Render text
    {
        simple_renderer_set_shader(sr, SHADER_FOR_TEXT);
        for (size_t i = 0; i < editor->tokens.count; ++i) {
            Token token = editor->tokens.items[i];
            Vec2f pos = token.position;
            Vec4f color = vec4fs(1);
            switch (token.kind) {
            case TOKEN_PREPROC:
                color = hex_to_vec4f(0x95A99FFF);
                break;
            case TOKEN_KEYWORD:
                color = hex_to_vec4f(0xFFDD33FF);
                break;
            case TOKEN_COMMENT:
                color = hex_to_vec4f(0xCC8C3CFF);
                break;
            case TOKEN_STRING:
                color = hex_to_vec4f(0x73c936ff);
                break;
            default:
            {}
            }
            free_glyph_atlas_render_line_sized(atlas, sr, token.text, token.text_len, &pos, color);
            // TODO: the max_line_len should be calculated based on what's visible on the screen right now
            if (max_line_len < pos.x) max_line_len = pos.x;
        }
        simple_renderer_flush(sr);
    }

    Vec2f cursor_pos = vec2fs(0.0f);
    {
        size_t cursor_row = editor_cursor_row(editor);
        Line line = editor->lines.items[cursor_row];
        size_t cursor_col = editor->cursor - line.begin;
        cursor_pos.y = -((float)cursor_row + CURSOR_OFFSET) * FREE_GLYPH_FONT_SIZE;
        cursor_pos.x = free_glyph_atlas_cursor_pos(
                           atlas,
                           editor->data.items + line.begin, line.end - line.begin,
                           vec2f(0.0, cursor_pos.y),
                           cursor_col
                       );
    }

    // Render cursor
    simple_renderer_set_shader(sr, SHADER_FOR_COLOR);
    {
        float CURSOR_WIDTH = 5.0f;
        Uint32 CURSOR_BLINK_THRESHOLD = 500;
        Uint32 CURSOR_BLINK_PERIOD = 1000;
        Uint32 t = SDL_GetTicks() - editor->last_stroke;

        sr->verticies_count = 0;
        if (t < CURSOR_BLINK_THRESHOLD || t/CURSOR_BLINK_PERIOD%2 != 0) {
            simple_renderer_solid_rect(
                sr,
                cursor_pos, vec2f(CURSOR_WIDTH, FREE_GLYPH_FONT_SIZE),
                vec4fs(1));
        }

        simple_renderer_flush(sr);
    }

    // Update camera
    {
        if (max_line_len > 1000.0f) {
            max_line_len = 1000.0f;
        }

        float target_scale = w/3/(max_line_len*0.75); // TODO: division by 0

        Vec2f target = cursor_pos;
        float offset = 0.0f;

        if (target_scale > 3.0f) {
            target_scale = 3.0f;
        } else {
            offset = cursor_pos.x - w/3/sr->camera_scale;
            if (offset < 0.0f) offset = 0.0f;
            target = vec2f(w/3/sr->camera_scale + offset, cursor_pos.y);
        }

        sr->camera_vel = vec2f_mul(
                             vec2f_sub(target, sr->camera_pos),
                             vec2fs(2.0f));
        sr->camera_scale_vel = (target_scale - sr->camera_scale) * 2.0f;

        sr->camera_pos = vec2f_add(sr->camera_pos, vec2f_mul(sr->camera_vel, vec2fs(DELTA_TIME)));
        sr->camera_scale = sr->camera_scale + sr->camera_scale_vel * DELTA_TIME;
    }
}

void editor_update_selection(Editor *e, bool shift)
{
    if (shift) {
        if (!e->selection) {
            e->selection = true;
            e->select_begin = e->cursor;
        }
    } else {
        if (e->selection) {
            e->selection = false;
        }
    }
}

void editor_clipboard_copy(Editor *e)
{
    if (e->selection) {
        size_t begin = e->select_begin;
        size_t end = e->cursor;
        if (begin > end) SWAP(size_t, begin, end);

        e->clipboard.count = 0;
        sb_append_buf(&e->clipboard, &e->data.items[begin], end - begin + 1);
        sb_append_null(&e->clipboard);

        if (SDL_SetClipboardText(e->clipboard.items) < 0) {
            fprintf(stderr, "ERROR: SDL ERROR: %s\n", SDL_GetError());
        }
    }
}

void editor_clipboard_paste(Editor *e)
{
    char *text = SDL_GetClipboardText();
    size_t text_len = strlen(text);
    if (text_len > 0) {
        editor_insert_buf(e, text, text_len);
    } else {
        fprintf(stderr, "ERROR: SDL ERROR: %s\n", SDL_GetError());
    }
    SDL_free(text);
}