const std = @import("std");
const http = @import("http.zig");
const Allocator = std.mem.Allocator;

pub const Voice = struct {
    file_id: []const u8,
    duration: ?i64 = null,
};

pub const VideoNote = struct {
    file_id: []const u8,
    duration: ?i64 = null,
};

pub const Message = struct {
    message_id: i64,
    chat: struct {
        id: i64,
        @"type": []const u8 = "private",
    },
    text: ?[]const u8 = null,
    voice: ?Voice = null,
    video_note: ?VideoNote = null,
};

pub const Update = struct {
    update_id: i64,
    message: ?Message = null,
};

pub const GetUpdatesResponse = struct {
    ok: bool,
    result: []Update = &.{},
};

pub const GetFileResponse = struct {
    ok: bool,
    result: ?struct {
        file_path: ?[]const u8 = null,
    } = null,
};

pub const SendMessageBody = struct {
    chat_id: i64,
    text: []const u8,
    reply_to_message_id: ?i64 = null,
};

/// Parsed JSON result that also owns the raw JSON body.
/// Must call deinit() to free both.
pub fn OwnedParsed(comptime T: type) type {
    return struct {
        parsed: std.json.Parsed(T),
        raw_body: []u8,
        allocator: Allocator,

        pub fn deinit(self: *@This()) void {
            self.parsed.deinit();
            self.allocator.free(self.raw_body);
        }
    };
}

pub const TelegramBot = struct {
    allocator: Allocator,
    token: []const u8,
    api_base: []const u8,

    pub fn init(allocator: Allocator, token: []const u8) !TelegramBot {
        const api_base = try std.fmt.allocPrint(allocator, "https://api.telegram.org/bot{s}", .{token});
        return .{
            .allocator = allocator,
            .token = token,
            .api_base = api_base,
        };
    }

    pub fn deinit(self: *TelegramBot) void {
        self.allocator.free(self.api_base);
    }

    pub fn getUpdates(self: *TelegramBot, offset: i64, timeout: u32) !OwnedParsed(GetUpdatesResponse) {
        const url = try std.fmt.allocPrint(self.allocator, "{s}/getUpdates?offset={d}&timeout={d}", .{ self.api_base, offset, timeout });
        defer self.allocator.free(url);

        const body = try http.httpGet(self.allocator, url);

        const parsed = std.json.parseFromSlice(GetUpdatesResponse, self.allocator, body, .{ .ignore_unknown_fields = true }) catch {
            self.allocator.free(body);
            return error.HttpRequestFailed;
        };

        return .{
            .parsed = parsed,
            .raw_body = body,
            .allocator = self.allocator,
        };
    }

    pub fn getFilePath(self: *TelegramBot, file_id: []const u8) ![]u8 {
        const url = try std.fmt.allocPrint(self.allocator, "{s}/getFile?file_id={s}", .{ self.api_base, file_id });
        defer self.allocator.free(url);

        const body = try http.httpGet(self.allocator, url);
        defer self.allocator.free(body);

        const parsed = try std.json.parseFromSlice(GetFileResponse, self.allocator, body, .{ .ignore_unknown_fields = true });
        defer parsed.deinit();

        if (parsed.value.result) |result| {
            if (result.file_path) |fp| {
                return self.allocator.dupe(u8, fp);
            }
        }
        return error.HttpRequestFailed;
    }

    pub fn downloadFile(self: *TelegramBot, file_path: []const u8, dest: []const u8) !void {
        const url = try std.fmt.allocPrint(self.allocator, "https://api.telegram.org/file/bot{s}/{s}", .{ self.token, file_path });
        defer self.allocator.free(url);

        try http.downloadToFile(self.allocator, url, dest);
    }

    pub fn sendMessage(self: *TelegramBot, chat_id: i64, text: []const u8, reply_to: ?i64) !void {
        const url = try std.fmt.allocPrint(self.allocator, "{s}/sendMessage", .{self.api_base});
        defer self.allocator.free(url);

        const msg = SendMessageBody{
            .chat_id = chat_id,
            .text = text,
            .reply_to_message_id = reply_to,
        };

        const json_body = std.json.Stringify.valueAlloc(self.allocator, msg, .{}) catch return;
        defer self.allocator.free(json_body);

        const resp = http.httpPostJson(self.allocator, url, json_body) catch return;
        self.allocator.free(resp);
    }

    pub fn sendVoice(self: *TelegramBot, chat_id: i64, ogg_path: []const u8, reply_to: ?i64) !void {
        const url = try std.fmt.allocPrint(self.allocator, "{s}/sendVoice", .{self.api_base});
        defer self.allocator.free(url);

        const chat_id_str = try std.fmt.allocPrint(self.allocator, "{d}", .{chat_id});
        defer self.allocator.free(chat_id_str);

        var fields_buf: [2][2][]const u8 = undefined;
        var field_count: usize = 1;
        fields_buf[0] = .{ "chat_id", chat_id_str };

        var reply_str: ?[]u8 = null;
        defer if (reply_str) |s| self.allocator.free(s);

        if (reply_to) |r| {
            reply_str = try std.fmt.allocPrint(self.allocator, "{d}", .{r});
            fields_buf[1] = .{ "reply_to_message_id", reply_str.? };
            field_count = 2;
        }

        const resp = try http.httpPostMultipart(
            self.allocator,
            url,
            "voice",
            ogg_path,
            "voice.ogg",
            fields_buf[0..field_count],
        );
        self.allocator.free(resp);
    }
};