const QuitText = struct {
    const text = "Press ctrl+c to quit.";

    pub fn element(this: *@This()) App.Element {
        return .{ .ptr = this, .vtable = &.{ .content = content } };
    }

    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
        _ = ctx;
        assert(cells.len == @as(usize, size.x) * @as(usize, size.y));

        const row = 2;
        const col = size.x / 2 -| (text.len / 2);
        const anchor = (row * size.x) + col;

        for (text, 0..) |cp, idx| {
            cells[anchor + idx].style.fg = .white;
            cells[anchor + idx].style.bg = .black;
            cells[anchor + idx].cp = cp;

            // NOTE do not write over the contents of this `Container`'s `Size`
            if (anchor + idx == cells.len - 1) break;
        }
    }
};

const MouseDraw = struct {
    position: ?zterm.Point = null,

    pub fn element(this: *@This()) App.Element {
        return .{
            .ptr = this,
            .vtable = &.{
                .handle = handle,
                .content = content,
            },
        };
    }

    fn handle(ctx: *anyopaque, _: *App.Model, event: App.Event) !void {
        const this: *@This() = @ptrCast(@alignCast(ctx));
        switch (event) {
            .mouse => |mouse| this.position = .{ .x = mouse.x, .y = mouse.y },
            else => this.position = null,
        }
    }

    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
        assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
        const this: *@This() = @ptrCast(@alignCast(ctx));

        if (this.position) |pos| {
            const idx = @as(usize, size.x) * @as(usize, pos.y) + @as(usize, pos.x);
            cells[idx].cp = 'x';
            cells[idx].style.fg = .red;
        }
    }
};

pub fn main() !void {
    errdefer |err| log.err("Application Error: {any}", .{err});

    var gpa: std.heap.DebugAllocator(.{}) = .init;
    defer if (gpa.deinit() == .leak) log.err("memory leak", .{});

    const allocator = gpa.allocator();

    var threaded_io: std.Io.Threaded = .init(allocator, .{});
    defer threaded_io.deinit();

    var app: App = .init(threaded_io.ioBasic(), .{});
    var renderer = zterm.Renderer.Buffered.init(allocator);
    defer renderer.deinit();

    var input_field: App.Input(.accept) = .init(allocator, &app.queue, .init(.black, .blue));
    var mouse_draw: MouseDraw = .{};
    var second_mouse_draw: MouseDraw = .{};
    var quit_text: QuitText = .{};

    var container = try App.Container.init(allocator, .{
        .rectangle = .{ .fill = .grey },
        .layout = .{
            .direction = .vertical,
            .padding = .all(5),
        },
    }, quit_text.element());
    defer container.deinit();

    try container.append(try App.Container.init(allocator, .{
        .rectangle = .{ .fill = .lightgrey },
        .size = .{
            .grow = .horizontal,
            .dim = .{ .y = 1 },
        },
    }, input_field.element()));

    var nested_container: App.Container = try .init(allocator, .{
        .border = .{
            .sides = .all,
            .color = .black,
        },
        .rectangle = .{ .fill = .lightgrey },
        .layout = .{
            .separator = .{
                .enabled = true,
                .color = .black,
            },
        },
    }, .{});
    try nested_container.append(try .init(allocator, .{
        .rectangle = .{ .fill = .lightgrey },
    }, mouse_draw.element()));
    try nested_container.append(try .init(allocator, .{
        .rectangle = .{ .fill = .lightgrey },
    }, second_mouse_draw.element()));
    try container.append(nested_container);

    try app.start();
    defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});

    // event loop
    while (true) {
        const event = app.nextEvent();
        log.debug("received event: {s}", .{@tagName(event)});

        // pre event handling
        switch (event) {
            .key => |key| if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } })) app.quit(),
            .accept => |input| {
                defer allocator.free(input);
                log.debug("Accepted input '{s}'", .{input});
            },
            .err => |err| log.err("Received {s} with message: {s}", .{ @errorName(err.err), err.msg }),
            else => {},
        }

        container.handle(&app.model, event) catch |err| app.postEvent(.{
            .err = .{
                .err = err,
                .msg = "Container Event handling failed",
            },
        });

        // post event handling
        switch (event) {
            .quit => break,
            else => {},
        }

        container.resize(&app.model, try renderer.resize());
        container.reposition(&app.model, .{});
        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
        try renderer.flush();
    }
}

pub const panic = App.panic_handler;
const log = std.log.scoped(.default);

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

const App = zterm.App(
    struct {},
    union(enum) {
        accept: []u8,
    },
);