const std = @import("std");

const c = @cImport({
    @cInclude("SDL.h");
    @cInclude("SDL_ttf.h");
});

const assert = @import("std").debug.assert;

pub fn main() !void {
    const window_width = 300;
    const window_height = 500;
    const column_width = 100;

    if (c.SDL_Init(c.SDL_INIT_VIDEO) != 0) {
        c.SDL_Log("Unable to initialize SDL: %s", c.SDL_GetError());
        return error.SDLInitializationFailed;
    }
    defer c.SDL_Quit();

    const screen = c.SDL_CreateWindow("Document Map Viewer", c.SDL_WINDOWPOS_UNDEFINED, c.SDL_WINDOWPOS_UNDEFINED, window_width, window_height, c.SDL_WINDOW_OPENGL) orelse
        {
        c.SDL_Log("Unable to create window: %s", c.SDL_GetError());
        return error.SDLInitializationFailed;
    };
    defer c.SDL_DestroyWindow(screen);

    const renderer = c.SDL_CreateRenderer(screen, -1, 0) orelse {
        c.SDL_Log("Unable to create renderer: %s", c.SDL_GetError());
        return error.SDLInitializationFailed;
    };
    defer c.SDL_DestroyRenderer(renderer);

    const source_code = @embedFile("GapProbeScan.cs");
    const file_name = "GapProbeScan.cs";

    const color_result: c_int = c.SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
    if (color_result != 0) {
        c.SDL_Log("Unable to set draw color: %d", color_result);
        return error.SDLInitializationFailed;
    }

    // https://github.com/cirosantilli/cpp-cheat/blob/e52ed4b838e2697d8f44ab5bef3e7a170705d48e/sdl/ttf.c
    const ttf_init_result: c_int = c.TTF_Init();
    if (ttf_init_result != 0) {
        c.SDL_Log("Unable to init TTF: %d", ttf_init_result);
        return error.TTFInitializationFailed;
    }
    defer c.TTF_Quit();

    const text_color: c.SDL_Color = c.SDL_Color {
        .r = 0,
        .g = 0,
        .b = 0,
        .a = 255
    };

    // TODO: can we embed this file?
    const font: ?*c.TTF_Font = c.TTF_OpenFont("FreeSans.ttf", 24);
    if (font == null) {
        const err = c.TTF_GetError();
        c.SDL_Log("Unable to load font: %s", err);
        return error.TTFFontLoadFailed;
    }

    const surface: [*c]c.SDL_Surface = c.TTF_RenderText_Solid(font, file_name, text_color);
    if (surface == null) {
        c.SDL_Log("Unable to render text");
        return error.RenderTextFailed;
    }
    defer c.SDL_FreeSurface(surface);

    const texture: ?*c.SDL_Texture = c.SDL_CreateTextureFromSurface(renderer, surface);
    if (texture == null) {
        c.SDL_Log("Unable to create texture from surface");
        return error.CreateTextureFailed;
    }
    defer c.SDL_DestroyTexture(texture);

    const rect = c.SDL_Rect {
        .x = 0,
        .y = 0,
        .w = surface.*.w,
        .h = surface.*.h,
    };

    // const surface = c.SDL_GetWindowSurface(screen);

    var quit = false;
    while (!quit) {
        var event: c.SDL_Event = undefined;
        while (c.SDL_PollEvent(&event) != 0) {
            switch (event.@"type") {
                c.SDL_QUIT => {
                    quit = true;
                },
                else => {},
            }
        }

        const initial_color_result = c.SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
        if (initial_color_result != 0) {
            c.SDL_Log("Unable to set draw color: %d", initial_color_result);
            return error.SDLInitializationFailed;
        }

        var x: c_int = 0;
        while (x < window_width) : (x += 1) {
            var y: c_int = 0;
            while (y < window_height) : (y += 1) {
                const draw_result = c.SDL_RenderDrawPoint(renderer, x, y);
                if (draw_result != 0) {
                    c.SDL_Log("Unable to draw point: %d", draw_result);
                    return error.SDLDrawingFailed;
                }
            }
        }

        var i: usize = 0;
        var column: c_int = 0;
        x = 0;
        var y: c_int = surface.*.h;
        // white: false, black: true
        var color: bool = false;
        while (i < source_code.len) : (i += 1) {
            if (source_code[i] == 10) {
                y += 1;
                if (y > window_height) {
                    y = 0;
                    column += 1;
                    // std.debug.print("Column: {any}, x: {any}\n", .{column, column*column_width});
                }
                x = column * column_width;

                continue;
            }

            if (source_code[i] == 32 and color) {
                color = false;
                const white_color_result = c.SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
                if (white_color_result != 0) {
                    c.SDL_Log("Unable to set draw color: %d", white_color_result);
                    return error.SDLInitializationFailed;
                }
            } else if (source_code[i] != 32 and !color) {
                color = true;
                const black_color_result = c.SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
                if (black_color_result != 0) {
                    c.SDL_Log("Unable to set draw color: %d", black_color_result);
                    return error.SDLInitializationFailed;
                }
            }

            if (x < (column + 1) * column_width) {
                const draw_result = c.SDL_RenderDrawPoint(renderer, x, y);
                if (draw_result != 0) {
                    c.SDL_Log("Unable to draw point: %d", draw_result);
                    return error.SDLDrawingFailed;
                }
            } else {
                const red_color_result = c.SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
                if (red_color_result != 0) {
                    c.SDL_Log("Unable to set draw color: %d", red_color_result);
                    return error.SDLInitializationFailed;
                }

                const draw_result = c.SDL_RenderDrawPoint(renderer, (column + 1) * column_width - 1, y);
                if (draw_result != 0) {
                    c.SDL_Log("Unable to draw point: %d", draw_result);
                    return error.SDLDrawingFailed;
                }

                if (!color) {
                    const white_color_result = c.SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
                    if (white_color_result != 0) {
                        c.SDL_Log("Unable to set draw color: %d", white_color_result);
                        return error.SDLInitializationFailed;
                    }
                } else {
                    const black_color_result = c.SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
                    if (black_color_result != 0) {
                        c.SDL_Log("Unable to set draw color: %d", black_color_result);
                        return error.SDLInitializationFailed;
                    }
                }
            }

            x += 1;
        }

        // Display text
        if (c.SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255) != 0) {
            c.SDL_Log("Unable to set draw color");
        }

        if (c.SDL_RenderCopy(renderer, texture, null, &rect) != 0) {
            c.SDL_Log("Unable to render copy");
        }

        c.SDL_RenderPresent(renderer);

        c.SDL_Delay(17);
    }
}