package main

import (
	"errors"
	"net/http"
	"strings"

	"github.com/duke-git/lancet/v2/validator"
	"github.com/gin-gonic/gin"
	"resty.dev/v3"
)

// newServer 创建并配置 HTTP 服务。
func newServer(db *DB, client *resty.Client) *gin.Engine {
	gin.SetMode(gin.ReleaseMode)
	server := gin.Default()
	server.Use(corsMiddleware())
	registerRoutes(server, db, client)
	return server
}

// corsMiddleware 允许浏览器跨域访问接口。
func corsMiddleware() gin.HandlerFunc {
	return func(ctx *gin.Context) {
		ctx.Header("Access-Control-Allow-Origin", "*")
		ctx.Header("Access-Control-Allow-Methods", "GET, OPTIONS")
		ctx.Header("Access-Control-Allow-Headers", "Origin, Content-Type, Accept, Authorization")

		if ctx.Request.Method == http.MethodOptions {
			ctx.AbortWithStatus(http.StatusNoContent)
			return
		}

		ctx.Next()
	}
}

// registerRoutes 注册当前服务公开的 HTTP 路由。
func registerRoutes(server *gin.Engine, db *DB, client *resty.Client) {
	server.GET("/", handleArticleRequest(db, client))
}

// handleArticleRequest 处理文章查询请求：校验参数，读取缓存或抓取源站。
func handleArticleRequest(db *DB, client *resty.Client) gin.HandlerFunc {
	return func(ctx *gin.Context) {
		articleID := strings.TrimSpace(ctx.Query("article_id"))
		if articleID == "" {
			ctx.JSON(http.StatusNotFound, response{Ok: false})
			return
		}

		if !validator.IsNumberStr(articleID) {
			ctx.JSON(http.StatusBadRequest, response{
				Ok:    false,
				Error: "article_id 应为数字",
			})
			return
		}

		html, err := getArticleHTML(db, client, articleID)
		if err != nil {
			ctx.JSON(articleErrorStatusCode(err), createErr(err))
			return
		}

		ctx.JSON(http.StatusOK, response{
			Ok:   true,
			Html: html,
		})
	}
}

// articleErrorStatusCode 将文章抓取错误映射为合适的 HTTP 状态码。
func articleErrorStatusCode(err error) int {
	if errors.Is(err, errArticleContentNotFound) || errors.Is(err, errArticleContentParseFailed) {
		return http.StatusNotFound
	}

	return http.StatusInternalServerError
}