//! WASM Demo - zcatgui running in a web browser
//!
//! Build with:
//!   zig build wasm-demo
//!
//! Then serve the `web/` directory and open index.html

const std = @import("std");
const zcatgui = @import("zcatgui");

// Use WASM allocator
const allocator = std.heap.wasm_allocator;

// Global state (since WASM is single-threaded)
var ctx: ?*zcatgui.Context = null;
var backend: ?*WasmBackend = null;
var running: bool = true;

// Demo state
var counter: i32 = 0;
var checkbox_checked: bool = false;
var slider_value: f32 = 0.5;
var text_buffer: [256]u8 = [_]u8{0} ** 256;
var text_len: usize = 0;

const WasmBackend = zcatgui.backend.wasm.WasmBackend;

/// Called once at startup
export fn wasm_main() void {
    init() catch |err| {
        zcatgui.backend.wasm.log("Init error: {}", .{err});
    };
}

/// Called every frame
export fn wasm_frame() void {
    if (ctx) |c| {
        frame(c) catch |err| {
            zcatgui.backend.wasm.log("Frame error: {}", .{err});
        };
    }
}

fn init() !void {
    // Initialize backend
    const be = try allocator.create(WasmBackend);
    be.* = try WasmBackend.init(800, 600);
    backend = be;

    // Initialize context
    const c = try allocator.create(zcatgui.Context);
    c.* = try zcatgui.Context.init(allocator, 800, 600);
    ctx = c;

    zcatgui.backend.wasm.log("zcatgui WASM initialized!", .{});
}

fn frame(c: *zcatgui.Context) !void {
    const be = backend.?;

    // Process events
    while (be.backend().pollEvent()) |event| {
        switch (event) {
            .quit => running = false,
            .key => |k| c.input.handleKeyEvent(k),
            .mouse => |m| {
                // Update mouse position
                c.input.setMousePos(m.x, m.y);
                // Update mouse buttons
                if (m.button) |btn| {
                    c.input.setMouseButton(btn, m.pressed);
                }
                // Update scroll
                if (m.scroll_x != 0 or m.scroll_y != 0) {
                    c.input.addScroll(m.scroll_x, m.scroll_y);
                }
            },
            .resize => |r| {
                // Handle resize
                _ = r;
            },
            .text_input => |t| {
                // Handle text input
                if (text_len < text_buffer.len - 1) {
                    const slice = t.text[0..t.len];
                    for (slice) |char| {
                        if (text_len < text_buffer.len - 1) {
                            text_buffer[text_len] = char;
                            text_len += 1;
                        }
                    }
                }
            },
        }
    }

    // Begin frame
    c.beginFrame();

    // Set theme
    const theme = zcatgui.Style.Theme.dark;

    // Title
    c.layout.row_height = 40;
    zcatgui.labelEx(c, "zcatgui WASM Demo", .{
        .alignment = .center,
        .color = theme.primary,
    });

    c.layout.row_height = 20;
    zcatgui.label(c, "Running in WebAssembly!");

    // Spacing
    c.layout.row_height = 10;
    zcatgui.label(c, "");

    // Counter section
    c.layout.row_height = 32;

    var buf: [64]u8 = undefined;
    const counter_text = std.fmt.bufPrint(&buf, "Counter: {d}", .{counter}) catch "Counter: ?";
    zcatgui.label(c, counter_text);

    // Buttons
    if (zcatgui.button(c, "Increment")) {
        counter += 1;
    }

    if (zcatgui.button(c, "Decrement")) {
        counter -= 1;
    }

    if (zcatgui.button(c, "Reset")) {
        counter = 0;
    }

    // Checkbox
    c.layout.row_height = 10;
    zcatgui.label(c, "");
    c.layout.row_height = 32;

    if (zcatgui.checkbox(c, &checkbox_checked, "Enable feature")) {
        // Checkbox changed
    }

    // Progress bar
    c.layout.row_height = 10;
    zcatgui.label(c, "");
    c.layout.row_height = 32;

    var slider_buf: [32]u8 = undefined;
    const slider_label = std.fmt.bufPrint(&slider_buf, "Progress: {d:.0}%", .{slider_value * 100}) catch "Progress: ?";
    zcatgui.label(c, slider_label);

    // Progress bar showing value
    _ = zcatgui.widgets.progress.bar(c, slider_value);

    // Info
    c.layout.row_height = 10;
    zcatgui.label(c, "");
    c.layout.row_height = 24;
    zcatgui.labelEx(c, "Press keys to type, Tab to navigate", .{
        .alignment = .center,
        .color = zcatgui.Color.rgb(128, 128, 128),
    });

    // End frame
    c.endFrame();

    // Render
    var fb = zcatgui.render.Framebuffer.init(allocator, 800, 600) catch return;
    defer fb.deinit();

    // Clear with background color
    fb.clear(theme.background);

    // Execute draw commands
    var renderer = zcatgui.render.SoftwareRenderer.init(&fb);
    renderer.executeAll(c.commands.items);

    // Present to canvas
    be.backend().present(&fb);
}