#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright (c) 2025-2026 Renato Xavier da Silveira Rosa
# See [LICENSE](./LICENSE) or [BSD-3-Clause-Clear](https://spdx.org/licenses/BSD-3-Clause-Clear.html)
# Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
"""Generic TTS Backend for handling text-to-speech conversion.

This module provides a generic TTS backend that can be used to convert text to speech using various TTS engines. It defines a `GenericTTSBackend` class that can be initialized with a specific backend command, language, and voice. The class provides methods to normalize paths, determine input and output flags based on the type of input/output (file or directory), build the command for the TTS engine, and run the command.

Classes:
    
    GenericTTSBackend:
        
        Parameters:
            backend_cmd (str): Command or executable for the backend.
            language (Optional[str]): Language code for TTS output.
            voice (Optional[str]): Voice name for TTS output.
        
        Methods:
            _normalize_path(value: PathLike) -> Path: Normalize a string or Path to Path.
            
            gen_input_flag(input_path: Path) -> str: Return backend flag for input file or directory.
            
            gen_output_flag(output_path: Path) -> str: Return backend flag for output file or directory.
            
            _build_command(input_source: PathLike, output_dest: PathLike) -> list[str]: Build command list for subprocess.
            
            run(input_source: PathLike, output_dest: PathLike) -> subprocess.CompletedProcess: Execute backend command.

"""

import subprocess
from pathlib import Path
from typing import Optional, Union

PathLike = Union[str, Path]

from .vendor_utils import build_run_command


class GenericTTSBackend:
    """Generic TTS backend for handling text-to-speech conversion.

    Parameters:
        backend_cmd (str): Command or executable for the backend.
        language (Optional[str]): Language code for TTS output.
        voice (Optional[str]): Voice name for TTS output.
    """
   
    FLAGS = {}
    INTERMEDIATE_TXT = False
    DEFAULT_SPEAKER = None
    DEFAULT_SAMPLE = None
    SUPPORTED_AUDIO_FORMATS = {
        # subclasses may override this
        ".m4b": "m4b",
        ".wav": "wav",
        ".flac": "flac",
        ".mp3": "mp3",
        ".ogg": "ogg",
    }
    
    _INPUT_FLAG_MAP = lambda x: [
        "--input-dir", x] if x else ["--input-file", x]
    
    _OUTPUT_FLAG_MAP = lambda x: [
        "--output-dir", x] if x else ["--output-file", x]

    def __init__(self,**kwargs):
        for k,v in kwargs.items():
            setattr(self, k, v)


    def _normalize_path(self, value: PathLike) -> Path:
        if isinstance(value, Path):
            return value.resolve()
        else:
            return Path(value).resolve()


    def gen_input_flag(self, input_path: Path) -> str:
        return self._INPUT_FLAG_MAP(self._normalize_path(input_path).is_dir())


    def gen_output_flag(self, output_path: Path) -> str:
        return self._OUTPUT_FLAG_MAP(self._normalize_path(output_path).is_dir())


    def _build_command(self, input_source: PathLike, output_dest: PathLike) -> list[str]:
        command = [self.backend_cmd]
        command.extend(self.gen_input_flag(input_source))
        command.extend(self.gen_output_flag(output_dest))
        for flag_name, var_name in self.FLAGS.items():
            if getattr(self, flag_name, None) is not None:
                command.extend([
                    f"--{flag_name.replace('_', '-')}", 
                    getattr(self, var_name)])
        return command
    
    def run(self,
            input_source: PathLike,
            output_dest: PathLike,
            **kwargs
            ) -> subprocess.CompletedProcess:
        
        

        completed = subprocess.run(
            self._build_command(input_source, output_dest), 
            cwd=str(self._normalize_path(input_source).parent), 
            check=True)
        
        if self.INTERMEDIATE_TXT:
            txt_file = self._normalize_path(input_source).with_suffix(".txt")
            if txt_file.exists():
                completed = subprocess.run(
                    self._build_command(txt_file, output_dest),
                    cwd=str(self._normalize_path(input_source).parent),
                    check=True
                )


        return completed