// Refer to:
//      https://github.com/raysan5/raylib/blob/master/examples/models/models_heightmap_rendering.c
//
// This program is under ./LICENSE.raylib.txt.
//

const std = @import("std");
const builtin = @import("builtin");
const rl = @import("raylib");

const MainWinWidth: i32 = 800;
const MainWinHeight: i32 = 600;

fn testDrawRectangle() void {
    const rec = rl.Rectangle{ .x = 50, .y = 50, .width = 400, .height = 150 };
    rl.drawRectangleRec(rec, rl.Color{ .r = 64, .g = 166, .b = 217, .a = 55 });
}

fn testDrawText() !void {
    const raylib_version = "Raylib v" ++ rl.RAYLIB_VERSION;
    const zig_version = "Zig-" ++ builtin.zig_version_string;
    rl.drawText(zig_version, 70, 70, 20, .dark_blue);
    rl.drawText(raylib_version, 70, 100, 20, .dark_blue);
    rl.drawText("2025/11", 70, 130, 20, .dark_blue);

    const font = try rl.getFontDefault();
    const position = rl.Vector2{ .x = 70, .y = 160 };
    rl.drawTextEx(font, "Hello with custom font", position, 24, 2, .gray);
}

//--------
// main()
//--------
pub fn main() !void {
    rl.setConfigFlags(.{ .vsync_hint = true, .window_resizable = true, .window_hidden = true }); //  Enable VSYNC
    rl.initWindow(MainWinWidth, MainWinHeight, "raylib [core] example - basic window");
    defer rl.closeWindow(); // Close window and OpenGL context

    const title_bar_icon = try rl.loadImage("./resources/z.png");
    rl.setWindowIcon(title_bar_icon);
    rl.unloadImage(title_bar_icon);

    // Define our custom camera to look into our 3d world
    var camera = rl.Camera3D{
        .position = rl.Vector3{ .x = 18, .y = 18, .z = 18 }, // Camera position
        .target = rl.Vector3{ .x = 0, .y = 0, .z = 0 }, // Camera looking at point
        .up = rl.Vector3{ .x = 0, .y = 1, .z = 0 }, // Camera up Vector (rotation towards target)
        .fovy = 48, // Camera field-of-view Y
        .projection = .perspective, // Camera projection type
    };
    const image = try rl.loadImage("./resources/istockphoto_com-1209065219-128.png"); // https://www.istockphoto.com  search "grayscale height map"
    defer rl.unloadImage(image); // Unload heightmap image from RAM, already uploaded to VRAM

    const texture = try rl.loadTextureFromImage(image); // Convert image to texture (VRAM)
    defer rl.unloadTexture(texture); // Unload texture

    const mesh = rl.genMeshHeightmap(image, rl.Vector3{ .x = 16, .y = 8, .z = 16 }); // Generate heightmap mesh (RAM and VRAM)
    const model = try rl.loadModelFromMesh(mesh); // Load model from generated mesh
    defer rl.unloadModel(model); // Unload model

    model.materials[0].maps[@intFromEnum(rl.MATERIAL_MAP_DIFFUSE)].texture = texture;

    const mapPosition = rl.Vector3{ .x = -8, .y = 0, .z = -8 }; // Define model position

    rl.setTargetFPS(60); // Set our game to run at 60 frames-per-second

    const mapColor = [_]f32{ (255.0 - 73.0) / 255.0, (255.0 - 113.0) / 255.0, (255.0 - 166.0) / 255.0 };

    var delayShowWindow: i32 = 1;

    while (!rl.windowShouldClose()) {
        // Update
        rl.updateCamera(&camera, .orbital); // Set an orbital camera mode

        rl.beginDrawing();
        defer rl.endDrawing();

        { // Draw
            testDrawRectangle();
            try testDrawText();
            //------------------------
            //-- Raylib draw height map
            //------------------------
            rl.clearBackground(.black);
            {
                rl.beginMode3D(camera);
                const color = rl.Color{ .r = mapColor[0] * 255, .g = mapColor[1] * 255, .b = mapColor[2] * 255, .a = 255 };
                rl.drawModel(model, mapPosition, 1, color);
                rl.drawGrid(20, 1);
                rl.endMode3D();
            }
            rl.drawTexture(texture, MainWinWidth - texture.width - 20, 20, .white);
            rl.drawRectangleLines(MainWinWidth - texture.width - 20, 20, texture.width, texture.height, .white);

            const str = rl.textFormat("%i FPS\n", .{rl.getFPS()});
            rl.drawText(str, 10, 10, 20, .gray);

            rl.drawText("Raylib with Zig", 50, 250, 20, .ray_white);
        }

        if (delayShowWindow == 0) {
            rl.clearWindowState(rl.ConfigFlags{ .window_hidden = true });
        }
        if (delayShowWindow >= 0) {
            delayShowWindow -= 1;
        }
    } // while end
}