from typing import Dict, Optional
from fastapi import Header

# Translation dictionaries
TRANSLATIONS = {
    "en": {
        "job_not_found": "Job not found",
        "invalid_extension": "Invalid file extension: {ext}. Allowed: {allowed}",
        "single_file_only": "Only one file allowed per task",
        "queue_update_triggered": "Queue update triggered",
        "task_created": "Task created successfully",
        "server_error": "Internal server error",
        "job_not_completed": "Job not completed. Current status: {status}",
        "results_not_found": "Results not found on disk",
        "job_deleted": "Job {job_id} deleted successfully",
        "use_post_jobs": "Use POST /api/v1/jobs/create for now",
        "task_not_found": "Task not found",
        "task_not_in_queue": "Task is not in queue",
    },
    "zh": {
        "job_not_found": "任务不存在",
        "invalid_extension": "文件后缀无效: {ext}。允许: {allowed}",
        "single_file_only": "每次任务只能上传一个文件",
        "queue_update_triggered": "已触发队列更新",
        "task_created": "任务创建成功",
        "server_error": "服务器内部错误",
        "job_not_completed": "任务未完成。当前状态: {status}",
        "results_not_found": "未找到结果文件",
        "job_deleted": "任务 {job_id} 已删除",
        "use_post_jobs": "请使用 POST /api/v1/jobs/create 接口",
        "task_not_found": "任务不存在",
        "task_not_in_queue": "任务不在队列中",
    }
}

DEFAULT_LANG = "en"

def get_language(accept_language: Optional[str] = Header(None)) -> str:
    """
    Determine the preferred language from the Accept-Language header.
    Defaults to 'en' if not specified or not supported.
    """
    if not accept_language:
        return DEFAULT_LANG

    # Simple parsing: check if 'zh' is in the header
    # A more robust parser could be added if needed
    if "zh" in accept_language.lower():
        return "zh"

    return DEFAULT_LANG

def get_text(key: str, lang: str = DEFAULT_LANG, **kwargs) -> str:
    """
    Get translated text for a given key and language.
    Supports string formatting with kwargs.
    """
    # Fallback to default language if lang not supported
    if lang not in TRANSLATIONS:
        lang = DEFAULT_LANG

    # Fallback to key if message not found in language
    message = TRANSLATIONS[lang].get(key)
    if not message:
        # Try default language
        message = TRANSLATIONS[DEFAULT_LANG].get(key, key)

    try:
        return message.format(**kwargs)
    except KeyError:
        return message