//! Matrix client (scaffold) — conduwuit @ chaosmith.systems.
//!
//! HTTP via curl subprocess behind a narrow seam (native TLS swap later).
//! Sync loop + send + login. No olm/megolm: rooms must be unencrypted
//! (trusted_private_chat without encryption).

const std = @import("std");
const Io = std.Io;
const letta = @import("letta.zig");

pub const HOMESERVER = "https://matrix.chaosmith.systems";
pub const DEVICE_NAME = "inferon-harness";

// ------------------------------------------------------------- transport ---

/// HTTP via curl subprocess. Returns body (allocated; caller frees).
fn http(alloc: std.mem.Allocator, io: Io, method: []const u8, url: []const u8, token: ?[]const u8, json_body: ?[]const u8) ![]u8 {
    var argv: std.ArrayList([]const u8) = .empty;
    defer argv.deinit(alloc);
    try argv.appendSlice(alloc, &.{ "curl", "-sS", "-m", "25", "-X", method });
    if (token) |t| {
        // NOTE: no defer-free — h must outlive the spawn below (argv holds it).
        // Leaks one small string per call; fine for the harness, revisit with
        // the native-TLS rewrite.
        const h = try std.fmt.allocPrint(alloc, "Authorization: Bearer {s}", .{t});
        try argv.appendSlice(alloc, &.{ "-H", h });
    }
    if (json_body) |b| {
        try argv.appendSlice(alloc, &.{ "-H", "Content-Type: application/json", "-d", b });
    }
    try argv.append(alloc, url);

    var child = try std.process.spawn(io, .{
        .argv = argv.items,
        .stdin = .ignore,
        .stdout = .pipe,
        .stderr = .ignore,
    });
    const out = child.stdout.?;
    var buf: std.ArrayList(u8) = .empty;
    errdefer buf.deinit(alloc);
    var tmp: [16 * 1024]u8 = undefined;
    while (true) {
        const got = out.readStreaming(io, &.{&tmp}) catch break;
        if (got == 0) break;
        try buf.appendSlice(alloc, tmp[0..got]);
    }
    _ = child.wait(io) catch {};
    return buf.toOwnedSlice(alloc);
}

// ------------------------------------------------------------- api calls ---

pub const Session = struct { token: []u8, user_id: []u8 }; // caller frees both

pub fn login(alloc: std.mem.Allocator, io: Io, user: []const u8, password: []const u8) !Session {
    const body = try std.fmt.allocPrint(alloc,
        \\{{"type":"m.login.password","identifier":{{"type":"m.id.user","user":"{s}"}},"password":"{s}","initial_device_display_name":"{s}"}}
    , .{ user, password, DEVICE_NAME });
    defer alloc.free(body);
    const resp = try http(alloc, io, "POST", HOMESERVER ++ "/_matrix/client/v3/login", null, body);
    defer alloc.free(resp);
    const tok = letta.jsonStr(alloc, resp, 0, "access_token") orelse return error.LoginFailed;
    errdefer alloc.free(tok.val);
    const uid = letta.jsonStr(alloc, resp, 0, "user_id") orelse return error.LoginFailed;
    return .{ .token = tok.val, .user_id = uid.val };
}

/// Send a text message. Returns event id (allocated; caller frees).
pub fn sendText(alloc: std.mem.Allocator, io: Io, token: []const u8, room: []const u8, body: []const u8) ![]u8 {
    const ts = Io.Clock.now(.real, io).nanoseconds;
    const url = try std.fmt.allocPrint(alloc, "{s}/_matrix/client/v3/rooms/{s}/send/m.room.message/infr-{d}", .{ HOMESERVER, room, ts });
    defer alloc.free(url);

    var esc: std.ArrayList(u8) = .empty;
    defer esc.deinit(alloc);
    for (body) |c| {
        switch (c) {
            '"' => try esc.appendSlice(alloc, "\\\""),
            '\\' => try esc.appendSlice(alloc, "\\\\"),
            '\n' => try esc.appendSlice(alloc, "\\n"),
            '\r', '\t' => try esc.appendSlice(alloc, " "),
            else => try esc.append(alloc, c),
        }
    }
    const payload = try std.fmt.allocPrint(alloc, "{{\"msgtype\":\"m.text\",\"body\":\"{s}\"}}", .{esc.items});
    defer alloc.free(payload);

    const resp = try http(alloc, io, "PUT", url, token, payload);
    defer alloc.free(resp);
    const ev = letta.jsonStr(alloc, resp, 0, "event_id") orelse return error.SendFailed;
    return ev.val;
}

/// Join a room by id (accepts invites).
pub fn joinRoom(alloc: std.mem.Allocator, io: Io, token: []const u8, room: []const u8) !void {
    const url = try std.fmt.allocPrint(alloc, "{s}/_matrix/client/v3/rooms/{s}/join", .{ HOMESERVER, room });
    defer alloc.free(url);
    const resp = try http(alloc, io, "POST", url, token, "{}");
    alloc.free(resp);
}

pub const Event = struct { sender: []u8, body: []u8 }; // both allocated

/// One sync poll. Returns message events + next `since` token. Caller frees.
/// (Sync first without a since token to establish one, then poll.)
pub fn sync(alloc: std.mem.Allocator, io: Io, token: []const u8, since: []const u8, timeout_ms: u32) !struct { events: []Event, next: []u8 } {
    const url = if (since.len > 0)
        try std.fmt.allocPrint(alloc, "{s}/_matrix/client/v3/sync?timeout={d}&since={s}", .{ HOMESERVER, timeout_ms, since })
    else
        try std.fmt.allocPrint(alloc, "{s}/_matrix/client/v3/sync?timeout=0", .{HOMESERVER});
    defer alloc.free(url);
    const resp = try http(alloc, io, "GET", url, token, null);
    defer alloc.free(resp);

    const next = if (letta.jsonStr(alloc, resp, 0, "next_batch")) |nb| nb.val else try alloc.dupe(u8, since);

    var events: std.ArrayList(Event) = .empty;
    errdefer events.deinit(alloc);

    var i: usize = 0;
    while (std.mem.indexOfPos(u8, resp, i, "\"m.room.message\"")) |pos| {
        defer i = pos + 15;
        const win_end = @min(resp.len, pos + 1500);
        const win = resp[pos..win_end];
        const sender = letta.jsonStr(alloc, win, 0, "sender") orelse continue;
        const body = letta.jsonStr(alloc, win, 0, "body") orelse {
            alloc.free(sender.val);
            continue;
        };
        events.append(alloc, .{ .sender = sender.val, .body = body.val }) catch {
            alloc.free(sender.val);
            alloc.free(body.val);
        };
    }
    return .{ .events = try events.toOwnedSlice(alloc), .next = next };
}

/// Create a direct chat room with `peer`; returns room id (allocated).
pub fn createDirect(alloc: std.mem.Allocator, io: Io, token: []const u8, peer: []const u8) ![]u8 {
    const body = try std.fmt.allocPrint(alloc,
        \\{{"preset":"trusted_private_chat","invite":["{s}"],"is_direct":true}}
    , .{peer});
    defer alloc.free(body);
    const resp = try http(alloc, io, "POST", HOMESERVER ++ "/_matrix/client/v3/createRoom", token, body);
    defer alloc.free(resp);
    const room = letta.jsonStr(alloc, resp, 0, "room_id") orelse {
        std.debug.print("matrix: createRoom failed, resp: {s}\n", .{resp});
        return error.CreateFailed;
    };
    return room.val;
}