namespace Spry.Tools {

    public class Mkconst : Object {

        private static bool show_version = false;
        private static string? output_file = null;
        private static string? namespace_name = null;
        private static string? const_name_override = null;

        private const OptionEntry[] options = {
            { "output", 'o', 0, OptionArg.FILENAME, ref output_file, "Output file path (default: stdout)", "FILE" },
            { "ns", '\0', 0, OptionArg.STRING, ref namespace_name, "Wrap const in namespace", "NAMESPACE" },
            { "name", 'n', 0, OptionArg.STRING, ref const_name_override, "Override const name (default: derived from filename)", "NAME" },
            { "version", 'v', 0, OptionArg.NONE, ref show_version, "Show version information", null },
            { null }
        };

        public static int main(string[] args) {
            try {
                var opt_context = new OptionContext("<INPUT_FILE> - Convert file content to a Vala string constant");
                opt_context.set_help_enabled(true);
                opt_context.add_main_entries(options, null);
                opt_context.set_description(
                    "Arguments:\n" +
                    "  INPUT_FILE         Input file (typically an HTML template file)\n" +
                    "\n" +
                    "The const name is derived from the input filename by converting to CAPITAL_SNAKE_CASE.\n" +
                    "For example, 'UserContentComponent.vala.html' becomes USER_CONTENT_COMPONENT_VALA_HTML.\n" +
                    "\n" +
                    "Output goes to stdout by default, or use -o to specify an output file."
                );
                opt_context.parse(ref args);
            } catch (OptionError e) {
                stderr.printf("Error: %s\n", e.message);
                stderr.printf("Run '%s --help' for more information.\n", args[0]);
                return 1;
            }

            if (show_version) {
                stdout.printf("spry-mkconst 0.1\n");
                return 0;
            }

            // Get input file from remaining arguments
            string? input_file = null;
            if (args.length > 1) {
                input_file = args[1];
            }

            if (input_file == null) {
                stderr.printf("Error: No input file specified.\n");
                stderr.printf("Run '%s --help' for more information.\n", args[0]);
                return 1;
            }

            try {
                var tool = new Mkconst();
                tool.process(input_file, output_file, namespace_name, const_name_override);
                return 0;
            } catch (Error e) {
                stderr.printf("%s\n", e.message);
                return 1;
            }
        }

        public void process(string input_path, string? output_path, string? ns_name, string? const_name) throws Error {
            // Check if input file exists
            var input_file = File.new_for_path(input_path);
            if (!input_file.query_exists()) {
                throw new IOError.NOT_FOUND(@"Error: Input file '$(input_path)' does not exist");
            }

            // Read input file
            string content = read_file_content(input_path);

            // Normalize line endings to Unix style
            content = content.replace("\r\n", "\n").replace("\r", "\n");

            // Derive const name from filename if not provided
            string actual_const_name;
            if (const_name != null) {
                actual_const_name = const_name;
            } else {
                actual_const_name = filename_to_const_name(input_path);
            }

            // Escape any triple quotes in content by replacing """ with \"\"\"
            string escaped_content = content.replace("\"\"\"", "\\\"\\\"\\\"");

            // Determine indentation based on namespace
            string indent = ns_name != null ? "    " : "";

            // Build output
            var output = new StringBuilder();

            // Write namespace if provided
            if (ns_name != null) {
                output.append(@"namespace $(ns_name) {\n\n");
            }

            // Write the const declaration
            // Remove trailing newline from content before wrapping in triple quotes
            string trimmed_content = escaped_content;
            if (trimmed_content.has_suffix("\n")) {
                trimmed_content = trimmed_content.substring(0, trimmed_content.length - 1);
            }
            output.append(@"$(indent)const string $(actual_const_name) = \"\"\"$(trimmed_content)\"\"\";\n");

            // Close namespace if provided
            if (ns_name != null) {
                output.append("}\n");
            }

            // Write output
            if (output_path != null) {
                write_file_content(output_path, output.str);
            } else {
                stdout.printf("%s", output.str);
            }
        }

        private string filename_to_const_name(string filepath) {
            // Get just the filename (without directory path)
            string basename = Path.get_basename(filepath);

            // Convert to CAPITAL_SNAKE_CASE
            // Assumes input is PascalCase with possible extensions
            // e.g., "UserContentComponent.vala.html" -> "USER_CONTENT_COMPONENT_VALA_HTML"
            var result = new StringBuilder();
            var prev_was_lower = false;
            var prev_was_upper = false;

            foreach (var c in basename.to_utf8()) {
                if (c == '.') {
                    // Convert dots to underscores
                    result.append("_");
                    prev_was_lower = false;
                    prev_was_upper = false;
                } else if (c == '-') {
                    // Convert dashes to underscores
                    result.append("_");
                    prev_was_lower = false;
                    prev_was_upper = false;
                } else if (c == '_') {
                    result.append("_");
                    prev_was_lower = false;
                    prev_was_upper = false;
                } else if (c.isupper()) {
                    if (prev_was_lower) {
                        // Transition from lower to upper, insert underscore
                        result.append("_");
                    } else if (result.len > 0 && prev_was_upper) {
                        // Check if this is end of an acronym (next char would be lower)
                        // We'll handle this in the next iteration
                    }
                    result.append(c.to_string());
                    prev_was_lower = false;
                    prev_was_upper = true;
                } else if (c.islower()) {
                    if (prev_was_upper && result.len > 1) {
                        // Check if previous char was part of an acronym
                        // e.g., "HTMLFile" -> we want "HTML_FILE"
                        // Look back to see if we have multiple uppercase before this
                        string current = result.str;
                        if (current.length >= 2) {
                            char prev_char = (char)current.get(current.length - 1);
                            char prev_prev_char = (char)current.get(current.length - 2);
                            if (prev_char.isupper() && prev_prev_char.isupper()) {
                                // Insert underscore before the last uppercase char
                                result.erase(result.len - 1);
                                result.append("_");
                                result.append(prev_char.to_string());
                            }
                        }
                    }
                    result.append(c.toupper().to_string());
                    prev_was_lower = true;
                    prev_was_upper = false;
                } else if (c.isdigit()) {
                    result.append(c.to_string());
                    prev_was_lower = false;
                    prev_was_upper = false;
                }
                // Ignore other characters
            }

            return result.str;
        }

        private string read_file_content(string path) throws Error {
            var file = File.new_for_path(path);
            var input_stream = new DataInputStream(file.read());
            var builder = new StringBuilder();

            string line;
            while ((line = input_stream.read_line(null)) != null) {
                builder.append(line);
                builder.append("\n");
            }
            input_stream.close();

            return builder.str;
        }

        private void write_file_content(string path, string content) throws Error {
            var file = File.new_for_path(path);
            
            // Ensure parent directory exists
            var parent = file.get_parent();
            if (parent != null && !parent.query_exists()) {
                parent.make_directory_with_parents();
            }

            var output_stream = new DataOutputStream(file.replace(null, false, FileCreateFlags.NONE));
            output_stream.put_string(content);
            output_stream.close();
        }
    }
}