//! https://wiki.theory.org/BitTorrentSpecification#Metainfo_File_Structure
const std = @import("std");
const bencode = @import("bencode.zig");
const MetaInfo = @This();

pub const Info = struct {
    pub const File = struct {
        name: []const u8,
        length: u64,
        path: []const u8,
    };
    piece_length: u64,
    pieces: []const u8,
    files: []File,
    pub fn parse(b: bencode.BValue) !Info {
        var d = b.asDict() catch return error.Malformatted;
        const pl = d.get("piece length") orelse return error.Malformatted;
        const pp = d.get("pieces") orelse return error.Malformatted;
        return .{
            .piece_length = pl.asInt(u64) catch return error.Malformatted,
            .pieces = pp.asString() catch return error.Malformatted,
            .files = &[_]File{},
        };
    }
};

info: Info,
announce: []const u8,

pub fn parse(b: bencode.BValue) !MetaInfo {
    var d = b.asDict() catch return error.Malformatted;
    const i = d.get("info") orelse return error.Malformatted;
    const a = d.get("announce") orelse return error.Malformatted;
    return .{
        .info = try Info.parse(i),
        .announce = a.asString() catch return error.Malformatted,
    };
}

test "sample" {
    const a = std.testing.allocator;
    const sample_str = @embedFile("sample.torrent");
    var b = try bencode.bdecodeBuf(a, sample_str);
    defer b.deinit(a);
    const mi = try MetaInfo.parse(b);
    try std.testing.expectEqualStrings("http://bittorrent-test-tracker.codecrafters.io/announce", mi.announce);
}