#define BASIC_IMPL
#include "../basic/basic.h"
#include "raylib.h"
#include "raymath.h"

#include "buffer.cpp"

Arena FrameArena;

using Vec2 = Vector2;
struct Rect2 {
    Vec2 min;
    Vec2 max;
};

Vec2 GetSize(Rect2 r) {
    Vec2 result = {r.max.x - r.min.x, r.max.y - r.min.y};
    return result;
}

Rectangle ToRectangle(Rect2 r) {
    Rectangle result = {r.min.x, r.min.y, r.max.x - r.min.x, r.max.y - r.min.y};
    return result;
}

// Render units - positions ready to draw, y
// World units - positions offset by screen movement
// Window units - positions inside the window (starts in left top of window)
// WindowWorld units - positions offset by a position inside the buffer

struct Window {
    Rect2 rect_in_world_units;
    Vec2  window_world_to_window_units;

    Array<Range> cursors;
    Buffer       buffer;
};

Vec2 WindowWorldToWindowUnits(Vec2 value, const Window &window) {
    Vec2 result = Vector2Subtract(value, window.window_world_to_window_units);
    return result;
}

Vec2 WorldToRenderUnits(Vec2 value, Vec2 camera_offset_world_to_render_units) {
    Vec2 result = Vector2Subtract(value, camera_offset_world_to_render_units);
    return result;
}

Vec2 WindowToWorldUnits(Vec2 value, const Window &window) {
    Vector2 result = Vector2Add(value, window.rect_in_world_units.min);
    return result;
}

Rect2 GetScreenRectRenderUnits() {
    Rect2 result = {
        {                      0,                        0},
        {(float)GetRenderWidth(), (float)GetRenderHeight()}
    };
    return result;
}

// Draw text using Font
// NOTE: chars spacing is NOT proportional to fontSize
void DrawString(Font font, String text, Vector2 position, float fontSize, float spacing, Color tint) {
    if (font.texture.id == 0) font = GetFontDefault(); // Security check in case of not valid font

    float textOffsetX = 0.0f; // Offset X to next character to draw

    float scaleFactor = fontSize / font.baseSize; // Character quad scaling factor

    for (int i = 0; i < text.len;) {
        // Get next codepoint from byte string and glyph index in font
        int codepointByteCount = 0;
        int codepoint          = GetCodepointNext(&text.data[i], &codepointByteCount);
        int index              = GetGlyphIndex(font, codepoint);

        if ((codepoint != ' ') && (codepoint != '\t')) {
            DrawTextCodepoint(font, codepoint, {position.x + textOffsetX, position.y}, fontSize, tint);
        }

        if (font.glyphs[index].advanceX == 0) textOffsetX += ((float)font.recs[index].width * scaleFactor + spacing);
        else textOffsetX += ((float)font.glyphs[index].advanceX * scaleFactor + spacing);

        i += codepointByteCount; // Move text bytes counter to next codepoint
    }
}

int main() {
    InitScratch();
    RunBufferTests();

    InitWindow(800, 600, "Hello");
    SetTargetFPS(60);

    InitArena(&FrameArena);
    float font_size    = 25;
    float font_spacing = 1;
    Font  font         = LoadFontEx("C:/Windows/Fonts/times.ttf", (int)font_size, NULL, 250);

    Array<Window> windows = {};
    windows.add({GetScreenRectRenderUnits()});
    {
        Buffer *buffer = &windows[0].buffer;
        InitBuffer(buffer);
        for (int i = 0; i < 100; i += 1) {
            Array<Edit> edits = {FrameArena};
            AddEdit(&edits, GetEnd(*buffer), Format(FrameArena, "line number: %d\n", i));
            ApplyEdits(buffer, edits);
        }
    }

    Vec2 camera_offset_world_to_render_units = {};
    while (!WindowShouldClose()) {
        {
            Window *focused_window = &windows[0];

            if (IsMouseButtonDown(MOUSE_BUTTON_LEFT) || IsKeyDown(KEY_SPACE)) {
                camera_offset_world_to_render_units = Vector2Subtract(camera_offset_world_to_render_units, GetMouseDelta());
            }

            float mouse_wheel = GetMouseWheelMove() * 48;
            focused_window->window_world_to_window_units.y -= mouse_wheel;
            focused_window->window_world_to_window_units.y = ClampBottom(focused_window->window_world_to_window_units.y, 0.f);

            for (int c = GetCharPressed(); c; c = GetCharPressed()) {
                String     string = "?";
                UTF8Result utf8   = UTF32ToUTF8((uint32_t)c);
                if (utf8.error == 0) {
                    string = {(char *)utf8.out_str, (int64_t)utf8.len};
                }

                Array<Edit> edits = {FrameArena};
                AddEdit(&edits, {}, string);
                ApplyEdits(&focused_window->buffer, edits);
            }
        }

        BeginDrawing();
        ClearBackground(RAYWHITE);

        ForItem(window, windows) {
            Rect2 window_rect_in_render_units = {
                WorldToRenderUnits(window.rect_in_world_units.min, camera_offset_world_to_render_units),
                WorldToRenderUnits(window.rect_in_world_units.max, camera_offset_world_to_render_units),
            };
            Rectangle rectangle_in_render_units = ToRectangle(window_rect_in_render_units);
            DrawRectangleRec(rectangle_in_render_units, WHITE);

            //
            // Line rendering
            //
            // @todo: how to constrain x?
            // @optimize: I could clip to visible on screen window_rectangle but I couldn't get it right
            Vec2    s           = GetSize(window_rect_in_render_units);
            float   line_offset = font_size;
            float   _line_min_y = (window.window_world_to_window_units.y) / line_offset;
            float   _line_max_y = (s.y + window.window_world_to_window_units.y) / line_offset;
            int64_t line_min_y  = (int64_t)floorf(_line_min_y);
            int64_t line_max_y  = (int64_t)ceilf(_line_max_y);

            Vec2 window_rect_in_render_units_size = GetSize(window_rect_in_render_units);
            BeginScissorMode((int)window_rect_in_render_units.min.x, (int)window_rect_in_render_units.min.y, (int)window_rect_in_render_units_size.x, (int)window_rect_in_render_units_size.y);
            for (int64_t line = line_min_y; line < line_max_y; line += 1) {
                if (line < 0) break;
                if (line >= window.buffer.lines.len) break;

                Range line_range = window.buffer.lines[line];

                Vec2 text_position_in_world_window_units = {0, line_offset * (float)line};
                Vec2 text_position_in_window_units       = WindowWorldToWindowUnits(text_position_in_world_window_units, window);
                Vec2 text_position_in_world_units        = WindowToWorldUnits(text_position_in_window_units, window);
                Vec2 text_position_in_render_units       = WorldToRenderUnits(text_position_in_world_units, camera_offset_world_to_render_units);

                //
                // Glyph inside the line rendering
                //
                String text = GetString(window.buffer, line_range);
                if (font.texture.id == 0) font = GetFontDefault();
                float textOffsetX = 0.0f;
                float scaleFactor = font_size / font.baseSize; // Character quad scaling factor
                for (int i = 0; i < text.len;) {
                    int        codepointByteCount = 0;
                    int        codepoint          = GetCodepointNext(&text.data[i], &codepointByteCount);
                    int        index              = GetGlyphIndex(font, codepoint);
                    GlyphInfo *glyph              = font.glyphs + index;
                    Vec2       glyph_position     = {text_position_in_render_units.x + textOffsetX, text_position_in_render_units.y};

                    float x_to_offset_by = ((float)glyph->advanceX * scaleFactor + font_spacing);
                    if (glyph->advanceX == 0) x_to_offset_by = ((float)font.recs[index].width * scaleFactor + font_spacing);

                    Vec2  cell_size = {x_to_offset_by, font_size};
                    Rect2 cell_rect = {glyph_position, Vector2Add(glyph_position, cell_size)};

                    DrawRectangleLinesEx(ToRectangle(cell_rect), 1, {255, 0, 0, 120});
                    if ((codepoint != ' ') && (codepoint != '\t')) {
                        DrawTextCodepoint(font, codepoint, glyph_position, font_size, BLACK);
                    }

                    textOffsetX += x_to_offset_by;
                    i += codepointByteCount; // Move text bytes counter to next codepoint
                }
            }
            EndScissorMode();
        }

        EndDrawing();
    }
}