package httpapi

import (
	"errors"
	"net/http"
	"strconv"
	"strings"
	"unicode/utf8"

	"cmroubao/backend-api/internal/domain"
	"cmroubao/backend-api/internal/platform/shunyunbao"

	"github.com/gin-gonic/gin"
)

func registerERPAdminAPI(routes gin.IRoutes, handler *adminHandlers) {
	routes.GET("/api/v1/erp-session", handler.erpSessionStatus)
	routes.POST("/api/v1/erp-session/captcha", handler.createERPCaptcha)
	routes.GET(
		"/api/v1/erp-session/captcha/:ticket",
		handler.erpCaptchaContent,
	)
	routes.POST("/api/v1/erp-session/login", handler.loginERP)
}

func (h *adminHandlers) erpSessionStatus(ctx *gin.Context) {
	ctx.Header("Cache-Control", "no-store")
	ctx.JSON(http.StatusOK, erpSessionResponse(h.services.ERP.Status()))
}

func (h *adminHandlers) createERPCaptcha(ctx *gin.Context) {
	status, err := h.services.ERP.FetchCaptcha(ctx.Request.Context())
	if err != nil {
		writeERPError(ctx, err)
		return
	}
	ctx.Header("Cache-Control", "no-store")
	ctx.JSON(http.StatusOK, gin.H{
		"session":        erpSessionResponse(status),
		"captcha_ticket": status.CaptchaTicket,
		"captcha_url":    "/api/v1/erp-session/captcha/" + status.CaptchaTicket,
	})
}

func (h *adminHandlers) erpCaptchaContent(ctx *gin.Context) {
	ticket := strings.TrimSpace(ctx.Param("ticket"))
	if !validERPTicket(ticket) {
		writeERPError(ctx, shunyunbao.ErrCaptchaTicketInvalid)
		return
	}
	image, err := h.services.ERP.OpenCaptcha(ticket)
	if err != nil || !strings.HasPrefix(image.ContentType, "image/") ||
		len(image.Content) == 0 {
		writeERPError(ctx, err)
		return
	}
	ctx.Header("Cache-Control", "no-store")
	ctx.Header("Content-Type", image.ContentType)
	ctx.Header("Content-Length", strconv.Itoa(len(image.Content)))
	ctx.Header("Content-Disposition", "inline")
	ctx.Data(http.StatusOK, image.ContentType, image.Content)
}

func (h *adminHandlers) loginERP(ctx *gin.Context) {
	if !hasMediaType(ctx, "application/json") {
		writePublicError(
			ctx,
			http.StatusUnsupportedMediaType,
			"UNSUPPORTED_MEDIA_TYPE",
			"application/json is required",
			false,
			gin.H{},
		)
		return
	}
	var request struct {
		CaptchaTicket string `json:"captcha_ticket"`
		CaptchaCode   string `json:"captcha_code"`
	}
	if err := decodeJSON(ctx, &request); err != nil ||
		!validERPTicket(request.CaptchaTicket) ||
		!validERPCaptchaCode(request.CaptchaCode) {
		writePublicError(
			ctx,
			http.StatusBadRequest,
			"ERP_LOGIN_INVALID",
			"ERP login request is invalid",
			false,
			gin.H{},
		)
		return
	}
	status, err := h.services.ERP.Login(
		ctx.Request.Context(),
		request.CaptchaTicket,
		request.CaptchaCode,
	)
	if err != nil {
		writeERPError(ctx, err)
		return
	}
	ctx.Header("Cache-Control", "no-store")
	ctx.JSON(http.StatusOK, erpSessionResponse(status))
}

func erpSessionResponse(status shunyunbao.SessionStatus) gin.H {
	return gin.H{
		"configured":    status.Configured,
		"authenticated": status.Authenticated,
		"captcha_ready": status.CaptchaReady,
	}
}

func validERPTicket(value string) bool {
	value = strings.TrimSpace(value)
	return len(value) == 43 && utf8.ValidString(value) &&
		!strings.ContainsAny(value, " \t\r\n")
}

func validERPCaptchaCode(value string) bool {
	value = strings.TrimSpace(value)
	if value == "" || len([]byte(value)) > 64 || !utf8.ValidString(value) {
		return false
	}
	for _, character := range value {
		if character < 32 || character == 127 {
			return false
		}
	}
	return true
}

func writeERPError(ctx *gin.Context, err error) {
	status := http.StatusInternalServerError
	code := "ERP_INTERNAL_ERROR"
	message := "ERP connection operation failed"
	retryable := false
	switch {
	case errors.Is(err, domain.ErrFreightSourceNotConfigured):
		status = http.StatusUnprocessableEntity
		code = "ERP_NOT_CONFIGURED"
		message = "ERP credentials are not configured"
	case errors.Is(err, domain.ErrFreightSourceSessionNeeded):
		status = http.StatusConflict
		code = "ERP_SESSION_REQUIRED"
		message = "ERP session is required"
	case errors.Is(err, shunyunbao.ErrCaptchaTicketInvalid):
		status = http.StatusConflict
		code = "ERP_CAPTCHA_INVALID"
		message = "ERP captcha must be requested again"
	case errors.Is(err, shunyunbao.ErrLoginRejected):
		status = http.StatusUnprocessableEntity
		code = "ERP_LOGIN_REJECTED"
		message = "ERP login was rejected"
	case errors.Is(err, domain.ErrFreightSourceProtocol):
		status = http.StatusBadGateway
		code = "ERP_RESPONSE_INVALID"
		message = "ERP response is invalid"
	case errors.Is(err, domain.ErrFreightSourceUnavailable):
		status = http.StatusServiceUnavailable
		code = "ERP_UNAVAILABLE"
		message = "ERP is temporarily unavailable"
		retryable = true
	}
	writePublicError(ctx, status, code, message, retryable, gin.H{})
}