use axum::{
    http::StatusCode,
    http::{HeaderMap, HeaderValue},
    response::{IntoResponse, Response},
};
use serde_json::Value;
use shared_contracts::api::ApiErrorPayload;

use crate::{api_response::json_error_body, request_context::RequestContext};

#[derive(Debug)]
pub struct AppError {
    status_code: StatusCode,
    code: &'static str,
    message: String,
    details: Option<Value>,
    headers: HeaderMap,
}

impl AppError {
    pub fn from_status(status_code: StatusCode) -> Self {
        let (code, message) = resolve_http_error(status_code);

        Self {
            status_code,
            code,
            message: message.to_string(),
            details: None,
            headers: HeaderMap::new(),
        }
    }

    pub fn code(&self) -> &'static str {
        self.code
    }

    pub fn status_code(&self) -> StatusCode {
        self.status_code
    }

    pub fn message(&self) -> &str {
        &self.message
    }

    pub fn body_text(&self) -> String {
        // 批处理任务不能只读 HTTP 状态文案，否则 DashScope 返回的真实失败原因会被压成“上游服务请求失败”。
        self.details
            .as_ref()
            .and_then(|details| details.get("message"))
            .and_then(Value::as_str)
            .map(str::trim)
            .filter(|message| !message.is_empty())
            .unwrap_or(self.message.as_str())
            .to_string()
    }

    pub fn with_message(mut self, message: impl Into<String>) -> Self {
        self.message = message.into();
        self
    }

    pub fn with_details(mut self, details: Value) -> Self {
        self.details = Some(details);
        self
    }

    pub fn with_header(mut self, name: &'static str, value: HeaderValue) -> Self {
        self.headers.insert(name, value);
        self
    }

    pub fn into_response_with_context(self, request_context: Option<&RequestContext>) -> Response {
        let status_code = self.status_code;
        let payload = self.to_payload();
        let mut response =
            (status_code, json_error_body(request_context, &payload)).into_response();
        response.headers_mut().extend(self.headers);
        response
    }

    fn to_payload(&self) -> ApiErrorPayload {
        ApiErrorPayload::new(self.code, self.message.clone(), self.details.clone())
    }
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        self.into_response_with_context(None)
    }
}

fn resolve_http_error(status_code: StatusCode) -> (&'static str, &'static str) {
    match status_code {
        StatusCode::BAD_REQUEST => ("BAD_REQUEST", "请求参数不合法"),
        StatusCode::UNAUTHORIZED => ("UNAUTHORIZED", "未授权访问"),
        StatusCode::FORBIDDEN => ("FORBIDDEN", "禁止访问"),
        StatusCode::NOT_FOUND => ("NOT_FOUND", "资源不存在"),
        StatusCode::NOT_IMPLEMENTED => ("NOT_IMPLEMENTED", "功能暂未实现"),
        StatusCode::CONFLICT => ("CONFLICT", "请求冲突"),
        StatusCode::TOO_MANY_REQUESTS => ("TOO_MANY_REQUESTS", "请求过于频繁"),
        StatusCode::BAD_GATEWAY => ("UPSTREAM_ERROR", "上游服务请求失败"),
        StatusCode::SERVICE_UNAVAILABLE => ("SERVICE_UNAVAILABLE", "服务暂不可用"),
        _ if status_code.is_client_error() => ("BAD_REQUEST", "请求参数不合法"),
        _ => ("INTERNAL_SERVER_ERROR", "服务器内部错误"),
    }
}