"""
OpenAPI 全局增强：元数据 + 统一 ErrorResponse 组件 + 领域错误码表。
"""

from fastapi import FastAPI
from fastapi.openapi.utils import get_openapi

from app.core.error_codes import ALL_ERROR_CODES, ERROR_CODE_ENUM

ERROR_RESPONSE_REF = "#/components/schemas/ErrorResponse"
ERROR_CODE_REF = "#/components/schemas/ErrorCode"

COMMON_ERROR_RESPONSES: dict[int, dict] = {
    400: {"description": "请求参数错误", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    401: {"description": "认证失败", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    403: {"description": "权限不足", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    404: {"description": "资源不存在", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    409: {"description": "资源冲突", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    422: {"description": "请求体验证失败", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    429: {
        "description": "配额已用尽（QUOTA_EXCEEDED）或请求频率超限（RATE_LIMITED）",
        "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}},
    },
    500: {"description": "内部服务器错误", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    502: {"description": "外部服务异常", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    503: {"description": "服务不可用", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
    504: {"description": "网关超时", "content": {"application/json": {"schema": {"$ref": ERROR_RESPONSE_REF}}}},
}


def error_responses(
    *status_codes: int,
    descriptions: dict[int, str] | None = None,
) -> dict[int, dict]:
    """Pick reusable OpenAPI error response entries by HTTP status code."""
    out: dict[int, dict] = {}
    for code in status_codes:
        entry = dict(COMMON_ERROR_RESPONSES[code])
        if descriptions and code in descriptions:
            entry["description"] = descriptions[code]
        out[code] = entry
    return out


def _error_code_catalog_markdown() -> str:
    lines = [
        "",
        "### 错误响应格式",
        "",
        "所有 HTTP 错误返回 `application/json`：",
        "",
        "```json",
        '{ "error_code": "NOT_FOUND", "message": "资源不存在", "request_id": "req_xxx" }',
        "```",
        "",
        "组件 `ErrorCode` / `DomainErrorCode` 列出机器可读码；`message` 为面向用户的说明。",
        "",
        "| error_code | HTTP | 域 | 说明 |",
        "|------------|------|-----|------|",
    ]
    for entry in ALL_ERROR_CODES:
        status = entry["http_status"]
        status_cell = str(status) if status else "—"
        lines.append(
            f"| `{entry['code']}` | {status_cell} | {entry['domain']} | {entry['description']} |"
        )
    return "\n".join(lines)


def custom_openapi(app: FastAPI) -> dict:
    if app.openapi_schema:
        return app.openapi_schema

    base_description = (
        "为老年用户提供 AI 驱动的回忆录创作服务：\n"
        "语音对话采集 → 素材沉淀 → 章节生成 → PDF 导出。"
    )

    openapi_schema = get_openapi(
        title="Life Echo API",
        version="1.0.0",
        summary="岁月留书 — 口述回忆录生产平台",
        description=base_description + _error_code_catalog_markdown(),
        routes=app.routes,
    )

    components = openapi_schema.setdefault("components", {})
    schemas = components.setdefault("schemas", {})

    schemas["ErrorCode"] = {
        "title": "ErrorCode",
        "type": "string",
        "enum": ERROR_CODE_ENUM,
        "description": "机器可读错误码（全局 + 领域）；完整说明见 API 描述中的错误码表。",
    }

    domain_codes = sorted(
        {e["code"] for e in ALL_ERROR_CODES if e["domain"] != "core"}
    )
    schemas["DomainErrorCode"] = {
        "title": "DomainErrorCode",
        "type": "string",
        "enum": domain_codes,
        "description": "业务领域错误码（auth / payment 等），与通用 ErrorCode 并存。",
    }

    schemas["ErrorResponse"] = {
        "title": "ErrorResponse",
        "type": "object",
        "required": ["error_code", "message", "request_id"],
        "properties": {
            "error_code": {
                "allOf": [{"$ref": ERROR_CODE_REF}],
                "description": "机器可读错误码",
                "example": "NOT_FOUND",
            },
            "message": {
                "type": "string",
                "description": "面向用户的错误说明",
                "example": "资源不存在",
            },
            "request_id": {
                "type": "string",
                "description": "请求追踪 ID",
                "example": "req_abc123",
            },
        },
    }

    app.openapi_schema = openapi_schema
    return app.openapi_schema