from fastapi import Request
from typing import Dict, Any, Optional

# Translation dictionaries
TRANSLATIONS = {
    "en": {
        "job_not_found": "Job not found",
        "task_not_found": "Task not found",
        "invalid_extension": "Invalid file extension: {ext}. Allowed: {allowed}",
        "single_file_only": "Only one file allowed per task",
        "job_not_completed": "Job not completed. Current status: {status}",
        "results_not_found": "Results not found on disk",
        "job_deleted": "Job {job_id} deleted successfully",
        "task_not_in_queue": "Task is not in queue",
        "use_create_endpoint": "Use POST /api/v1/jobs/create for now",
        "upload_endpoint": "Upload endpoint",
        "queue_update_triggered": "Queue update triggered"
    },
    "zh": {
        "job_not_found": "未找到任务",
        "task_not_found": "未找到任务",
        "invalid_extension": "文件后缀无效: {ext}。允许: {allowed}",
        "single_file_only": "每个任务仅允许上传一个文件",
        "job_not_completed": "任务未完成。当前状态: {status}",
        "results_not_found": "未在磁盘上找到结果文件",
        "job_deleted": "任务 {job_id} 已成功删除",
        "task_not_in_queue": "任务不在队列中",
        "use_create_endpoint": "请使用 POST /api/v1/jobs/create 接口",
        "upload_endpoint": "上传接口",
        "queue_update_triggered": "已触发队列更新"
    }
}

DEFAULT_LOCALE = "en"

def get_locale(request: Request) -> str:
    """
    Get locale from Accept-Language header.
    Simple implementation: checks if 'zh' is in the header.
    """
    accept_language = request.headers.get("accept-language", "")
    if "zh" in accept_language.lower():
        return "zh"
    return "en"

class I18n:
    def __init__(self, request: Request):
        self.locale = get_locale(request)

    def t(self, key: str, **kwargs) -> str:
        """
        Translate a key.
        If key not found, return key.
        Supports string formatting with kwargs.
        """
        messages = TRANSLATIONS.get(self.locale, TRANSLATIONS[DEFAULT_LOCALE])
        message = messages.get(key, TRANSLATIONS[DEFAULT_LOCALE].get(key, key))

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

async def get_i18n(request: Request) -> I18n:
    """Dependency for getting I18n instance"""
    return I18n(request)