const std = @import("std");
const builtin = @import("builtin");

const cli = @import("cli.zig");
const colors = @import("colors.zig");

/// Decode a base64 string, used for parsing out build artifacts generated by the CLI program's
/// build.zig which are stored in the executable as a module.
pub fn base64Decode(allocator: std.mem.Allocator, input: []const u8) ![]const u8 {
    const decoder = std.base64.Base64Decoder.init(
        std.base64.url_safe_no_pad.alphabet_chars,
        std.base64.url_safe_no_pad.pad_char,
    );
    const size = try decoder.calcSizeForSlice(input);
    const ptr = try allocator.alloc(u8, size);
    try decoder.decode(ptr, input);
    return ptr;
}

const icons = .{
    .check = "✅",
    .cross = "❌",
};

/// Print a success confirmation.
pub fn printSuccess() void {
    std.debug.print(" " ++ icons.check ++ "\n", .{});
}

/// Print a failure confirmation.
pub fn printFailure() void {
    std.debug.print(" " ++ icons.cross ++ "\n", .{});
}

const PrintContext = enum { success, failure };
/// Print some output in with a given context to stderr.
pub fn print(comptime context: PrintContext, comptime message: []const u8, args: anytype) !void {
    const writer = std.io.getStdErr().writer();
    switch (context) {
        .success => try writer.print(
            std.fmt.comptimePrint("{s} {s}\n", .{ icons.check, colors.green(message) }),
            args,
        ),
        .failure => try writer.print(
            std.fmt.comptimePrint("{s} {s}\n", .{ icons.cross, colors.red(message) }),
            args,
        ),
    }
}

/// Detects a Jetzig project directory either in the current directory or one of its parent
/// directories.
pub fn detectJetzigProjectDir() !std.fs.Dir {
    var dir = try std.fs.cwd().openDir(".", .{});
    const max_parent_dirs: usize = 100; // Prevent symlink loops or other weird stuff.

    for (0..max_parent_dirs) |_| {
        if (try isPath(dir, "build.zig", .file) and try isPath(dir, "src/app/views", .dir)) return dir;

        dir = dir.openDir("..", .{}) catch |err| {
            switch (err) {
                error.FileNotFound, error.NotDir => {
                    std.debug.print(
                        "Encountered unexpected detecting Jetzig project directory: {s}\n",
                        .{@errorName(err)},
                    );
                    return error.JetzigCommandError;
                },
                else => return err,
            }
        };
        continue;
    }

    std.debug.print(
        \\Exceeded maximum parent directory depth.
        \\Unable to detect Jetzig project directory.
        \\
    ,
        .{},
    );
    return error.JetzigCommandError;
}

fn isPath(dir: std.fs.Dir, sub_path: []const u8, path_type: enum { file, dir }) !bool {
    switch (path_type) {
        .file => {
            _ = dir.statFile(sub_path) catch |err| {
                switch (err) {
                    error.FileNotFound => return false,
                    else => return err,
                }
            };
            return true;
        },
        .dir => {
            var test_dir = dir.openDir(sub_path, .{}) catch |err| {
                switch (err) {
                    error.FileNotFound, error.NotDir => return false,
                    else => return err,
                }
            };
            test_dir.close();
            return true;
        },
    }
}

// Strip leading and trailing whitespace from a u8 slice.
pub inline fn strip(input: []const u8) []const u8 {
    return std.mem.trim(u8, input, &std.ascii.whitespace);
}

/// Attempts to confirm if a string input is in CamelCase. False if the first character is
/// not alphabetic lower-case or if the input contains underscores.
pub fn isCamelCase(input: []const u8) bool {
    if (input.len == 0) return false;
    if (!std.mem.containsAtLeast(u8, "ABCDEFGHIJKLMNOPQRSTUVWXYZ", 1, &[_]u8{input[0]})) return false;
    if (std.mem.containsAtLeast(u8, input, 1, "_")) return false;

    return true;
}

pub fn execCommand(allocator: std.mem.Allocator, argv: []const []const u8) !void {
    std.debug.print("[exec]", .{});
    for (argv) |arg| std.debug.print(" {s}", .{arg});
    std.debug.print("\n", .{});

    if (std.process.can_execv) {
        return std.process.execv(allocator, argv);
    } else {
        var dir = try detectJetzigProjectDir();
        defer dir.close();
        const path = try dir.realpathAlloc(allocator, ".");
        defer allocator.free(path);
        try runCommandStreaming(allocator, path, argv);
    }
}

pub fn runCommandStreaming(allocator: std.mem.Allocator, install_path: []const u8, argv: []const []const u8) !void {
    var child = std.process.Child.init(argv, allocator);
    child.stdin_behavior = .Ignore;
    child.stdout_behavior = .Inherit;
    child.stderr_behavior = .Inherit;
    child.cwd = install_path;

    try child.spawn();
    _ = try child.wait();
}

/// Runs a command as a child process in Jetzig project directory and verifies successful exit
/// code.
pub fn runCommand(allocator: std.mem.Allocator, argv: []const []const u8) !void {
    var dir = try detectJetzigProjectDir();
    defer dir.close();
    try runCommandInDir(allocator, argv, .{ .dir = dir });
}

const Dir = union(enum) {
    path: []const u8,
    dir: std.fs.Dir,
};

/// Runs a command as a child process in the given directory and verifies successful exit code.
pub fn runCommandInDir(allocator: std.mem.Allocator, argv: []const []const u8, dir: Dir) !void {
    const cwd_path = switch (dir) {
        .path => |capture| capture,
        .dir => |capture| try capture.realpathAlloc(allocator, "."),
    };
    defer if (dir == .dir) allocator.free(cwd_path);

    const result = std.process.Child.run(.{
        .allocator = allocator,
        .argv = argv,
        .cwd = cwd_path,
    }) catch |err| {
        switch (err) {
            error.FileNotFound => {
                printFailure();
                const cmd_str = try std.mem.join(allocator, " ", argv);
                defer allocator.free(cmd_str);
                std.debug.print(
                    \\Error: Could not execute command - executable '{s}' not found
                    \\Command: {s}
                    \\Working directory: {s}
                    \\
                , .{ argv[0], cmd_str, cwd_path });
                return error.JetzigCommandError;
            },
            else => return err,
        }
    };
    defer allocator.free(result.stdout);
    defer allocator.free(result.stderr);

    if (result.term.Exited != 0) {
        printFailure();
        if (result.stdout.len > 0) {
            std.debug.print("\n[stdout]:\n{s}\n", .{result.stdout});
        }
        if (result.stderr.len > 0) {
            std.debug.print("\n[stderr]:\n{s}\n", .{result.stderr});
        }
        return error.JetzigCommandError;
    } else {
        printSuccess();
    }
}

/// Generate a full GitHub URL for passing to `zig fetch`.
pub fn githubUrl(allocator: std.mem.Allocator) ![]const u8 {
    var client = std.http.Client{ .allocator = allocator };
    defer client.deinit();

    const url = "https://api.github.com/repos/jetzig-framework/jetzig/branches/main";
    const extra_headers = &[_]std.http.Header{.{ .name = "X-GitHub-Api-Version", .value = "2022-11-28" }};

    var response_storage = std.ArrayList(u8).init(allocator);
    defer response_storage.deinit();

    const fetch_result = try client.fetch(.{
        .location = .{ .url = url },
        .extra_headers = extra_headers,
        .response_storage = .{ .dynamic = &response_storage },
    });

    if (fetch_result.status != .ok) {
        std.debug.print("Error fetching from GitHub: {s}\n", .{url});
        return error.JetzigCommandError;
    }

    const parsed_response = try std.json.parseFromSlice(
        struct { commit: struct { sha: []const u8 } },
        allocator,
        response_storage.items,
        .{ .ignore_unknown_fields = true },
    );
    defer parsed_response.deinit();

    return try std.mem.concat(
        allocator,
        u8,
        &[_][]const u8{
            "https://github.com/jetzig-framework/jetzig/archive/",
            parsed_response.value.commit.sha,
            ".tar.gz",
        },
    );
}

/// Attempt to locate the main application executable in `zig-out/bin/`
pub fn locateExecutable(
    allocator: std.mem.Allocator,
    dir: std.fs.Dir,
    options: struct { relative: bool = false },
) !?[]const u8 {
    const file = dir.openFile(".jetzig", .{}) catch |err| {
        switch (err) {
            error.FileNotFound => return null,
            else => return err,
        }
    };
    const content = try file.readToEndAlloc(allocator, 1024);
    defer allocator.free(content);

    const exe_name = strip(content);
    const suffix = if (builtin.os.tag == .windows) ".exe" else "";
    const full_name = try std.mem.concat(allocator, u8, &[_][]const u8{ exe_name, suffix });
    defer allocator.free(full_name);

    // XXX: Will fail if user sets a custom install path.
    var bin_dir = try dir.openDir("zig-out/bin", .{ .iterate = true });
    defer bin_dir.close();

    var walker = try bin_dir.walk(allocator);
    defer walker.deinit();

    while (try walker.next()) |entry| {
        if (entry.kind == .file and std.mem.eql(u8, entry.path, full_name)) {
            if (options.relative) {
                return try std.fs.path.join(allocator, &[_][]const u8{ "zig-out", "bin", entry.path });
            } else {
                return try bin_dir.realpathAlloc(allocator, entry.path);
            }
        }
    }

    return null;
}

pub fn environmentBuildOption(environment: cli.Environment) []const u8 {
    return switch (environment) {
        inline else => |tag| "-Denvironment=" ++ @tagName(tag),
    };
}

pub fn unicodePrint(comptime fmt: []const u8, args: anytype) !void {
    if (builtin.os.tag == .windows) {
        // Windows-specific code
        const cp_out = try UTF8ConsoleOutput.init();
        defer cp_out.deinit();

        std.debug.print(comptime fmt, args);
    } else {
        // Non-Windows platforms just print normally
        std.debug.print(fmt, args);
    }
}
const UTF8ConsoleOutput = struct {
    original: c_uint,

    fn init() !UTF8ConsoleOutput {
        const original = std.os.windows.kernel32.GetConsoleOutputCP();
        if (original == 0) {
            return error.FailedToGetConsoleOutputCP;
        }
        const result = std.os.windows.kernel32.SetConsoleOutputCP(65001); // UTF-8 code page
        if (result == 0) {
            return error.FailedToSetConsoleOutputCP;
        }
        return .{ .original = original };
    }

    fn deinit(self: UTF8ConsoleOutput) void {
        _ = std.os.windows.kernel32.SetConsoleOutputCP(self.original);
    }
};