// Copyright (C) 2023-2026  Lightpanda (Selecy SAS)
//
// Francis Bouvier <francis@lightpanda.io>
// Pierre Tachoire <pierre@lightpanda.io>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

const std = @import("std");
const lp = @import("lightpanda");
const builtin = @import("builtin");
const Allocator = std.mem.Allocator;

const log = lp.log;
const App = lp.App;
const Config = lp.Config;
const SigHandler = @import("Sighandler.zig");
pub const panic = lp.crash_handler.panic;

pub const std_options: std.Options = .{
    .signal_stack_size = null,
};

pub fn main(init: std.process.Init) !void {
    // allocator
    // - in Debug mode we use the General Purpose Allocator to detect memory leaks
    // - in Release mode we use the c allocator
    var gpa_instance: std.heap.DebugAllocator(.{ .stack_trace_frames = 10 }) = .init;
    const gpa = if (builtin.mode == .Debug) gpa_instance.allocator() else std.heap.c_allocator;

    defer if (builtin.mode == .Debug) {
        if (gpa_instance.detectLeaks() != 0) std.process.exit(1);
    };

    // arena for main-specific allocations
    var main_arena_instance = std.heap.ArenaAllocator.init(gpa);
    const main_arena = main_arena_instance.allocator();
    defer main_arena_instance.deinit();

    run(gpa, main_arena, init.minimal.args) catch |err| {
        if (err == error.UserCancelled) std.process.exit(130);
        // error.AgentFailed: the agent thread reported the failure in-context.
        // lp.Agent.UserError: a user-facing message was already printed.
        if (err == error.AgentFailed or lp.Agent.isUserError(err)) std.process.exit(1);
        log.fatal(.app, "exit", .{ .err = err });
        std.process.exit(1);
    };
}

fn run(allocator: Allocator, main_arena: Allocator, proc_args: std.process.Args) !void {
    lp.core_dump.disableIfRequested();

    const args = try Config.parseArgs(main_arena, proc_args);
    defer args.deinit(main_arena);

    switch (args.mode) {
        .help => |tag| return args.printUsageAndExit(main_arena, tag, true),
        .version => |opts| {
            if (opts.check) {
                try lp.checkVersion(allocator, &args);
            } else {
                var stdout = std.Io.File.stdout().writerStreaming(lp.io, &.{});
                try stdout.interface.print("{s}\n", .{lp.build_config.version});
            }
            return std.process.cleanExit(lp.io);
        },
        .agent => |opts| if (opts.list_models) {
            try lp.Agent.listModels(allocator, opts);
            return std.process.cleanExit(lp.io);
        },
        else => {},
    }

    if (args.logLevel()) |ll| {
        log.opts.level = ll;
    }
    if (args.logFormat()) |lf| {
        log.opts.format = lf;
    }

    // Set log filter scopes.
    log.opts.scope_enabled = log.resolveFilterScopes(args.logFilterScopes().items);

    // must be installed before any other threads
    const sighandler = try main_arena.create(SigHandler);
    sighandler.* = .{ .arena = main_arena };
    try sighandler.install();

    // _app is global to handle graceful shutdown.
    var app = try App.init(allocator, &args);
    defer app.deinit();

    try sighandler.on(lp.Network.stop, .{&app.network});

    app.telemetry.record(.{ .run = {} });

    defer if (app.config.dumpMetricsOnExit()) {
        var writer = std.Io.File.stdout().writerStreaming(lp.io, &.{});
        lp.metrics.write(&writer.interface);
    };

    switch (args.mode) {
        .serve => |opts| {
            log.debug(.app, "startup", .{ .mode = "serve", .snapshot = app.snapshot.fromEmbedded() });
            const address = std.Io.net.IpAddress.parse(opts.host, opts.port) catch |err| {
                log.fatal(.app, "invalid server address", .{ .err = err, .host = opts.host, .port = opts.port });
                return args.printUsageAndExit(main_arena, .serve, false);
            };

            var server = lp.Server.init(app, address) catch |err| {
                if (err == error.AddressInUse) {
                    log.fatal(.app, "address already in use", .{
                        .host = opts.host,
                        .port = opts.port,
                        .hint = "Another process is already listening on this address. " ++
                            "Stop the other process or use --port to choose a different port.",
                    });
                } else {
                    log.fatal(.app, "server run error", .{ .err = err });
                }
                return err;
            };
            defer server.deinit();

            try sighandler.on(lp.Server.shutdown, .{server});

            app.network.run();
        },
        .fetch => |opts| {
            const urls = opts.url.items;

            if (urls.len == 0) {
                log.fatal(.app, "missing URL", .{});
                return error.MissingArgument;
            }

            // Plain (non-JSON) dump writes one document to stdout with no
            // framing, so it can't disambiguate more than one page.
            if (urls.len == 1) {
                log.debug(.app, "startup", .{
                    .mode = "fetch",
                    .dump_mode = opts.dump,
                    .url = urls[0],
                    .snapshot = app.snapshot.fromEmbedded(),
                });
            } else {
                if (opts.json == false) {
                    log.fatal(.app, "multiple URLs require --json", .{});
                    return error.InvalidArgument;
                }
                log.debug(.app, "startup", .{
                    .mode = "fetch",
                    .dump_mode = opts.dump,
                    .url_count = urls.len,
                    .snapshot = app.snapshot.fromEmbedded(),
                });
            }

            var fetch_opts = lp.FetchOpts{
                .wait_ms = opts.wait_ms,
                .wait_until = opts.wait_until,
                .wait_script = opts.wait_script,
                .inject_script = opts.inject_script,
                .wait_selector = opts.wait_selector,
                .dump_mode = opts.dump,
                .dump = .{
                    .strip = opts.strip_mode,
                    .with_base = opts.with_base,
                    .with_frames = opts.with_frames,
                },
                .json = opts.json,
            };

            var writer = std.Io.File.stdout().writerStreaming(lp.io, &.{});
            if (opts.dump != null or opts.json) {
                fetch_opts.writer = &writer.interface;
            }

            // Browser owns a V8 isolate, which has thread affinity — it must
            // be init/used/deinit on the same thread (fetchThread, below). So
            // we can't treat Browser like the above serve path treats Server.
            // We need Browser to be createdin fetchThread and to get a reference
            // to it here.
            var ft: FetchTerminator = .{};
            try sighandler.on(FetchTerminator.terminate, .{&ft});
            if (opts.terminate_ms) |ms| {
                try sighandler.deadline(ms);
            }

            var worker_thread = try std.Thread.spawn(.{}, fetchThread, .{ app, &ft, urls, fetch_opts });
            worker_thread.join();
        },
        .mcp => |opts| {
            log.info(.mcp, "starting server", .{});

            log.opts.format = .logfmt;

            // --port serves MCP over HTTP instead of stdio. It and --cdp-port
            // both need app.network's single listener, so they can't combine.
            if (opts.port) |port| {
                if (opts.cdp_port != null) {
                    log.fatal(.mcp, "port conflicts with cdp-port", .{ .hint = "both need the single network listener" });
                    return;
                }
                const address = std.Io.net.IpAddress.parse(opts.host, port) catch |err| {
                    log.fatal(.mcp, "invalid address", .{ .err = err, .host = opts.host, .port = port });
                    return;
                };
                const http_server = try lp.mcp.HttpServer.init(allocator, app);
                defer http_server.deinit();
                // Shutdown rides the already-registered Network.stop handler:
                // a signal stops the accept loop, run() returns, deinit joins.
                http_server.run(address) catch |err| {
                    log.fatal(.mcp, "mcp http error", .{ .err = err });
                };
                return;
            }

            var cdp_server: ?*lp.Server = null;
            if (opts.cdp_port) |port| {
                const address = std.Io.net.IpAddress.parse("127.0.0.1", port) catch |err| {
                    log.fatal(.mcp, "invalid cdp address", .{ .err = err, .port = port });
                    return;
                };
                cdp_server = try lp.Server.init(app, address);
                try sighandler.on(lp.Server.shutdown, .{cdp_server.?});
            }
            defer if (cdp_server) |s| s.deinit();

            var worker_thread = try std.Thread.spawn(.{}, mcpThread, .{ allocator, app });
            defer worker_thread.join();

            // mcp talks over stdio on mcpThread. Only run the CDP accept/read
            // loop when an optional CDP server was started; otherwise the main
            // thread just waits for the worker.
            if (cdp_server != null) {
                app.network.run();
            }
        },
        .agent => |opts| {
            log.info(.app, "starting agent", .{});

            // Ctrl-C cancels the current turn; signals never kill the
            // process. `/quit` (or Ctrl-D on an empty prompt) exits.
            sighandler.no_hard_exit = true;

            var sig_bridge: lp.Agent.SigBridge = .{};
            try sighandler.on(lp.Agent.SigBridge.onSignal, .{&sig_bridge});

            var failed: bool = false;
            var cancelled: bool = false;
            {
                var worker_thread = try std.Thread.spawn(.{}, agentThread, .{
                    allocator,
                    app,
                    opts,
                    &failed,
                    &cancelled,
                    &sig_bridge,
                });
                worker_thread.join();
            }

            if (cancelled) return error.UserCancelled;
            if (failed) return error.AgentFailed;
        },
        else => unreachable,
    }
}

fn agentThread(
    allocator: std.mem.Allocator,
    app: *App,
    opts: Config.Agent,
    failed: *bool,
    cancelled: *bool,
    sig_bridge: *lp.Agent.SigBridge,
) void {
    defer app.network.stop();

    var agent_instance = lp.Agent.init(allocator, app, opts) catch |err| {
        if (err == error.UserCancelled) {
            cancelled.* = true;
        } else {
            // UserError: message already printed inside Agent.init.
            if (!lp.Agent.isUserError(err)) log.fatal(.app, "agent init error", .{ .err = err });
            failed.* = true;
        }
        return;
    };
    sig_bridge.attach(agent_instance);
    defer agent_instance.deinit();
    defer sig_bridge.detach();

    if (agent_instance.ai_client) |cli| {
        app.telemetry.record(.{
            .llm = app.telemetry.llm_init(@tagName(cli), agent_instance.model),
        });
    } else {
        app.telemetry.record(.{
            .llm = app.telemetry.llm_init("nollm", null),
        });
    }

    if (!agent_instance.run()) {
        failed.* = true;
    }
}

const FetchTerminator = struct {
    mutex: std.Io.Mutex = .init,
    browser: ?*lp.Browser = null,

    fn storeBrowser(self: *FetchTerminator, browser: *lp.Browser) void {
        self.mutex.lockUncancelable(lp.io);
        defer self.mutex.unlock(lp.io);
        self.browser = browser;
    }

    fn releaseBrowser(self: *FetchTerminator) void {
        self.mutex.lockUncancelable(lp.io);
        defer self.mutex.unlock(lp.io);
        const b = self.browser orelse return;
        b.env.cancelTerminate();
        self.browser = null;
    }

    fn terminate(self: *FetchTerminator) void {
        self.mutex.lockUncancelable(lp.io);
        defer self.mutex.unlock(lp.io);
        const b = self.browser orelse return;
        b.env.terminate();
        self.browser = null;
    }
};

fn fetchThread(app: *App, ft: *FetchTerminator, urls: []const [:0]const u8, fetch_opts: lp.FetchOpts) void {
    defer app.network.stop();

    var browser: lp.Browser = undefined;
    browser.init(app, .{}, null) catch |err| {
        log.fatal(.app, "browser init error", .{ .err = err });
        return;
    };
    defer browser.deinit();

    ft.storeBrowser(&browser);
    // if this exits normally, we want to disarm the FetchTerminator so that
    // any subsequent sighandlers don't try to shutdown an already (or in-the-
    // process-of) shutting down browser/env
    defer ft.releaseBrowser();

    lp.fetch(app, &browser, urls, fetch_opts) catch |err| {
        log.fatal(.app, "fetch error", .{ .err = err, .url_count = urls.len });
    };
}

fn mcpThread(allocator: std.mem.Allocator, app: *App) void {
    defer app.network.stop();

    var stdout = std.Io.File.stdout().writerStreaming(lp.io, &.{});
    var mcp_server: *lp.mcp.Server = lp.mcp.Server.init(allocator, app, &stdout.interface) catch |err| {
        log.fatal(.mcp, "mcp init error", .{ .err = err });
        return;
    };
    defer mcp_server.deinit();

    var stdin_buf: [64 * 1024]u8 = undefined;
    var stdin = std.Io.File.stdin().readerStreaming(lp.io, &stdin_buf);
    lp.mcp.router.processRequests(mcp_server, &stdin.interface, std.Io.File.stdin()) catch |err| {
        log.fatal(.mcp, "mcp error", .{ .err = err });
    };
}