package handlers

import (
	"errors"
	"io"
	"log"
	"net"
	"net/http"
	"strings"
	"syscall"

	"github.com/gin-gonic/gin"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jackc/puddle/v2"

	"booklib/internal/auth"
	"booklib/internal/config"
	"booklib/internal/redispkg"
	"booklib/internal/scanner"
	"booklib/internal/store"
)

type H struct {
	cfg *config.Config
	st  *store.Store
	rdb *redispkg.R
	sc  *scanner.Scanner
}

func New(cfg *config.Config, st *store.Store, rdb *redispkg.R, sc *scanner.Scanner) *H {
	return &H{cfg: cfg, st: st, rdb: rdb, sc: sc}
}

func err(c *gin.Context, status int, code, msg string) {
	c.AbortWithStatusJSON(status, gin.H{"error": gin.H{"code": code, "message": msg}})
}

// dbErr 统一处理 store 层失败:记日志;连接类错误 503(Service Unavailable),其余 500
// 注:brief 里的 pgxpool.ErrClosedPool 在 pgx v5 不存在,实际由 puddle 原样透出,用它替代;
// PG 停机时池内连接先收到 SQLSTATE 57P01(administrator shutdown),故把 08xx/57Pxx 也归为 503
func dbErr(c *gin.Context, e error) {
	log.Printf("db: %v", e)
	status, code := http.StatusInternalServerError, "internal"
	var pgErr *pgconn.PgError
	connClass := errors.As(e, &pgErr) && (strings.HasPrefix(pgErr.Code, "08") || strings.HasPrefix(pgErr.Code, "57P"))
	if connClass || errors.Is(e, syscall.ECONNREFUSED) || errors.Is(e, io.ErrUnexpectedEOF) ||
		errors.Is(e, net.ErrClosed) || errors.Is(e, puddle.ErrClosedPool) {
		status, code = http.StatusServiceUnavailable, "unavailable"
	}
	err(c, status, code, "db error")
}

func (h *H) AuthMw() gin.HandlerFunc {
	return func(c *gin.Context) {
		hdr := c.GetHeader("Authorization")
		tok, ok := strings.CutPrefix(hdr, "Bearer ")
		if !ok {
			err(c, http.StatusUnauthorized, "unauthorized", "missing bearer token")
			return
		}
		cl, perr := auth.Parse(h.cfg.JWTSecret, tok)
		if perr != nil {
			err(c, http.StatusUnauthorized, "unauthorized", "invalid token")
			return
		}
		c.Set("uid", cl.UID)
		c.Set("role", cl.Role)
		c.Next()
	}
}

func (h *H) AdminOnly() gin.HandlerFunc {
	return func(c *gin.Context) {
		if c.GetString("role") != "admin" {
			err(c, http.StatusForbidden, "forbidden", "admin only")
			return
		}
		c.Next()
	}
}

func uid(c *gin.Context) int64    { return c.GetInt64("uid") }
func isAdmin(c *gin.Context) bool { return c.GetString("role") == "admin" }