// Copyright (C) 2023-2024  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 builtin = @import("builtin");
const Allocator = std.mem.Allocator;

const jsruntime = @import("jsruntime");

const App = @import("app.zig").App;
const Browser = @import("browser/browser.zig").Browser;
const server = @import("server.zig");

const parser = @import("netsurf");
const apiweb = @import("apiweb.zig");

pub const Types = jsruntime.reflect(apiweb.Interfaces);
pub const UserContext = apiweb.UserContext;
pub const IO = @import("asyncio").Wrapper(jsruntime.Loop);
const version = @import("build_info").git_commit;

const log = std.log.scoped(.cli);

pub const std_options = std.Options{
    // Set the log level to info
    .log_level = .debug,

    // Define logFn to override the std implementation
    .logFn = logFn,
};

pub fn main() !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 = std.heap.GeneralPurposeAllocator(.{}){};
    const alloc = if (builtin.mode == .Debug) gpa.allocator() else std.heap.c_allocator;

    defer if (builtin.mode == .Debug) {
        _ = gpa.detectLeaks();
    };

    var args_arena = std.heap.ArenaAllocator.init(alloc);
    defer args_arena.deinit();
    const args = try parseArgs(args_arena.allocator());

    switch (args.mode) {
        .help => args.printUsageAndExit(args.mode.help),
        .version => {
            std.debug.print("{s}\n", .{version});
            return std.process.cleanExit();
        },
        .serve => |opts| {
            const address = std.net.Address.parseIp4(opts.host, opts.port) catch |err| {
                log.err("address (host:port) {any}\n", .{err});
                return args.printUsageAndExit(false);
            };
            var app = try App.init(alloc, .{
                .run_mode = args.mode,
                .tls_verify_host = opts.tls_verify_host,
            });
            defer app.deinit();

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

            const timeout = std.time.ns_per_s * @as(u64, opts.timeout);
            server.run(app, address, timeout) catch |err| {
                log.err("Server error", .{});
                return err;
            };
        },
        .fetch => |opts| {
            log.debug("Fetch mode: url {s}, dump {any}", .{ opts.url, opts.dump });

            var app = try App.init(alloc, .{
                .run_mode = args.mode,
                .tls_verify_host = opts.tls_verify_host,
            });
            defer app.deinit();
            app.telemetry.record(.{ .run = {} });

            // vm
            const vm = jsruntime.VM.init();
            defer vm.deinit();

            // browser
            var browser = Browser.init(app);
            defer browser.deinit();

            var session = try browser.newSession({});

            // page
            const page = try session.createPage(null);

            _ = page.navigate(opts.url, null) catch |err| switch (err) {
                error.UnsupportedUriScheme, error.UriMissingHost => {
                    log.err("'{s}' is not a valid URL ({any})\n", .{ opts.url, err });
                    return args.printUsageAndExit(false);
                },
                else => {
                    log.err("'{s}' fetching error ({any})\n", .{ opts.url, err });
                    return err;
                },
            };

            try page.wait();

            // dump
            if (opts.dump) {
                try page.dump(std.io.getStdOut());
            }
        },
    }
}

const Command = struct {
    mode: Mode,
    exec_name: []const u8,

    const Mode = union(App.RunMode) {
        help: bool, // false when being printed because of an error
        fetch: Fetch,
        serve: Serve,
        version: void,
    };

    const Serve = struct {
        host: []const u8,
        port: u16,
        timeout: u16,
        tls_verify_host: bool,
    };

    const Fetch = struct {
        url: []const u8,
        dump: bool = false,
        tls_verify_host: bool,
    };

    fn printUsageAndExit(self: *const Command, success: bool) void {
        const usage =
            \\usage: {s} command [options] [URL]
            \\
            \\Command can be either 'fetch', 'serve' or 'help'
            \\
            \\fetch command
            \\Fetches the specified URL
            \\Example: {s} fetch --dump https://lightpanda.io/
            \\
            \\Options:
            \\--dump          Dumps document to stdout.
            \\                Defaults to false.
            \\
            \\--insecure_disable_tls_host_verification
            \\                Disables host verification on all HTTP requests.
            \\                This is an advanced option which should only be
            \\                set if you understand and accept the risk of
            \\                disabling host verification.
            \\
            \\serve command
            \\Starts a websocket CDP server
            \\Example: {s} serve --host 127.0.0.1 --port 9222
            \\
            \\Options:
            \\--host          Host of the CDP server
            \\                Defaults to "127.0.0.1"
            \\
            \\--port          Port of the CDP server
            \\                Defaults to 9222
            \\
            \\--timeout       Inactivity timeout in seconds before disconnecting clients
            \\                Defaults to 3 (seconds)
            \\
            \\--insecure_disable_tls_host_verification
            \\                Disables host verification on all HTTP requests.
            \\                This is an advanced option which should only be
            \\                set if you understand and accept the risk of
            \\                disabling host verification.
            \\
            \\version command
            \\Displays the version of {s}
            \\
            \\help command
            \\Displays this message
            \\
        ;
        std.debug.print(usage, .{ self.exec_name, self.exec_name, self.exec_name, self.exec_name });
        if (success) {
            return std.process.cleanExit();
        }
        std.process.exit(1);
    }
};

fn parseArgs(allocator: Allocator) !Command {
    var args = try std.process.argsWithAllocator(allocator);
    defer args.deinit();

    const exec_name = std.fs.path.basename(args.next().?);

    var cmd = Command{
        .mode = .{ .help = false },
        .exec_name = try allocator.dupe(u8, exec_name),
    };

    const mode_string = args.next() orelse "";
    const mode = std.meta.stringToEnum(App.RunMode, mode_string) orelse blk: {
        const inferred_mode = inferMode(mode_string) orelse return cmd;
        // "command" wasn't a command but an option. We can't reset args, but
        // we can create a new one. Not great, but this fallback is temporary
        // as we transition to this command mode approach.
        args.deinit();

        args = try std.process.argsWithAllocator(allocator);
        // skip the exec_name
        _ = args.skip();

        break :blk inferred_mode;
    };

    cmd.mode = switch (mode) {
        .help => .{ .help = true },
        .serve => .{ .serve = parseServeArgs(allocator, &args) catch return cmd },
        .fetch => .{ .fetch = parseFetchArgs(allocator, &args) catch return cmd },
        .version => .{ .version = {} },
    };
    return cmd;
}

fn inferMode(opt: []const u8) ?App.RunMode {
    if (opt.len == 0) {
        return .serve;
    }

    if (std.mem.eql(u8, opt, "--dump")) {
        return .fetch;
    }
    if (std.mem.startsWith(u8, opt, "--") == false) {
        return .fetch;
    }

    if (std.mem.eql(u8, opt, "--host")) {
        return .serve;
    }

    if (std.mem.eql(u8, opt, "--port")) {
        return .serve;
    }

    if (std.mem.eql(u8, opt, "--timeout")) {
        return .serve;
    }
    return null;
}

fn parseServeArgs(
    allocator: Allocator,
    args: *std.process.ArgIterator,
) !Command.Serve {
    var host: []const u8 = "127.0.0.1";
    var port: u16 = 9222;
    var timeout: u16 = 3;
    var tls_verify_host = true;

    while (args.next()) |opt| {
        if (std.mem.eql(u8, "--host", opt)) {
            const str = args.next() orelse {
                log.err("--host argument requires an value", .{});
                return error.InvalidMissingHost;
            };
            host = try allocator.dupe(u8, str);
            continue;
        }

        if (std.mem.eql(u8, "--port", opt)) {
            const str = args.next() orelse {
                log.err("--port argument requires an value", .{});
                return error.InvalidMissingPort;
            };

            port = std.fmt.parseInt(u16, str, 10) catch |err| {
                log.err("--port value is invalid: {}", .{err});
                return error.InvalidPort;
            };
            continue;
        }

        if (std.mem.eql(u8, "--timeout", opt)) {
            const str = args.next() orelse {
                log.err("--timeout argument requires an value", .{});
                return error.MissingTimeout;
            };

            timeout = std.fmt.parseInt(u16, str, 10) catch |err| {
                log.err("--timeout value is invalid: {}", .{err});
                return error.InvalidTimeout;
            };
            continue;
        }

        if (std.mem.eql(u8, "--insecure_tls_verify_host", opt)) {
            tls_verify_host = false;
            continue;
        }

        log.err("Unknown option to serve command: '{s}'", .{opt});
        return error.UnkownOption;
    }

    return .{
        .host = host,
        .port = port,
        .timeout = timeout,
        .tls_verify_host = tls_verify_host,
    };
}

fn parseFetchArgs(
    allocator: Allocator,
    args: *std.process.ArgIterator,
) !Command.Fetch {
    var dump: bool = false;
    var url: ?[]const u8 = null;
    var tls_verify_host = true;

    while (args.next()) |opt| {
        if (std.mem.eql(u8, "--dump", opt)) {
            dump = true;
            continue;
        }

        if (std.mem.eql(u8, "--insecure_disable_tls_host_verification", opt)) {
            tls_verify_host = false;
            continue;
        }

        if (std.mem.startsWith(u8, opt, "--")) {
            log.err("Unknown option to serve command: '{s}'", .{opt});
            return error.UnkownOption;
        }

        if (url != null) {
            log.err("Can only fetch 1 URL", .{});
            return error.TooManyURLs;
        }
        url = try allocator.dupe(u8, opt);
    }

    if (url == null) {
        log.err("A URL must be provided to the fetch command", .{});
        return error.MissingURL;
    }

    return .{
        .url = url.?,
        .dump = dump,
        .tls_verify_host = tls_verify_host,
    };
}

var verbose: bool = builtin.mode == .Debug; // In debug mode, force verbose.
fn logFn(
    comptime level: std.log.Level,
    comptime scope: @Type(.enum_literal),
    comptime format: []const u8,
    args: anytype,
) void {
    if (!verbose) {
        // hide all messages with level greater of equal to debug level.
        if (@intFromEnum(level) >= @intFromEnum(std.log.Level.debug)) return;
    }
    // default std log function.
    std.log.defaultLog(level, scope, format, args);
}