package customerverification

import (
	"errors"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"

	"backend/internal/platform/middleware"
)

type Handler struct {
	service *Service
}

func NewHandler(service *Service) *Handler {
	return &Handler{service: service}
}

type verificationResponse struct {
	ID        uuid.UUID `json:"id"`
	UserID    uuid.UUID `json:"user_id"`
	Status    string    `json:"status"`
	AdminNote string    `json:"admin_note"`
	CreatedAt string    `json:"created_at"`
	UpdatedAt string    `json:"updated_at"`
}

func toResponse(v *CustomerVerification) verificationResponse {
	return verificationResponse{
		ID:        v.ID,
		UserID:    v.UserID,
		Status:    v.Status,
		AdminNote: v.AdminNote,
		CreatedAt: v.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
		UpdatedAt: v.UpdatedAt.Format("2006-01-02T15:04:05Z07:00"),
	}
}

// Submit lets a logged-in customer upload their ID document (front + back)
// for review. Whether this step is required at all is decided by the admin
// (site.Settings.CustomerVerificationRequired) and enforced at checkout,
// not here -- a customer may always submit early.
func (h *Handler) Submit(c *gin.Context) {
	userID, ok := middleware.GetUserID(c)
	if !ok {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
		return
	}

	frontFile, frontHeader, err := c.Request.FormFile("front")
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "missing 'front' file"})
		return
	}
	defer frontFile.Close()
	backFile, backHeader, err := c.Request.FormFile("back")
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "missing 'back' file"})
		return
	}
	defer backFile.Close()

	v, err := h.service.Submit(c.Request.Context(), userID,
		DocumentInput{Reader: frontFile, ContentType: frontHeader.Header.Get("Content-Type")},
		DocumentInput{Reader: backFile, ContentType: backHeader.Header.Get("Content-Type")},
	)
	if err != nil {
		if errors.Is(err, ErrUnsupportedType) {
			c.JSON(http.StatusUnsupportedMediaType, gin.H{"error": "documents must be JPEG or PNG images"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to submit verification"})
		return
	}
	c.JSON(http.StatusCreated, toResponse(v))
}

// Me returns the caller's own verification status, or 404 if they haven't
// submitted anything yet (not an error -- the storefront treats this as
// "not started").
func (h *Handler) Me(c *gin.Context) {
	userID, ok := middleware.GetUserID(c)
	if !ok {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
		return
	}
	v, err := h.service.GetByUser(c.Request.Context(), userID)
	if err != nil {
		if errors.Is(err, ErrNotFound) {
			c.JSON(http.StatusNotFound, gin.H{"error": "no verification submitted"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to load verification"})
		return
	}
	c.JSON(http.StatusOK, toResponse(v))
}

// MyDocument streams the caller's own submitted document back to them
// (e.g. so the storefront can show what was uploaded).
func (h *Handler) MyDocument(c *gin.Context) {
	userID, ok := middleware.GetUserID(c)
	if !ok {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
		return
	}
	v, err := h.service.GetByUser(c.Request.Context(), userID)
	if err != nil {
		if errors.Is(err, ErrNotFound) {
			c.JSON(http.StatusNotFound, gin.H{"error": "no verification submitted"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to load verification"})
		return
	}
	h.serveDocument(c, v)
}

// ListAdmin lists submissions, optionally filtered by ?status=pending.
func (h *Handler) ListAdmin(c *gin.Context) {
	list, err := h.service.List(c.Request.Context(), c.Query("status"))
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to list verifications"})
		return
	}
	resp := make([]verificationResponse, 0, len(list))
	for _, v := range list {
		resp = append(resp, toResponse(v))
	}
	c.JSON(http.StatusOK, gin.H{"verifications": resp})
}

func (h *Handler) GetAdmin(c *gin.Context) {
	id, err := uuid.Parse(c.Param("id"))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid id"})
		return
	}
	v, err := h.service.Get(c.Request.Context(), id)
	if err != nil {
		if errors.Is(err, ErrNotFound) {
			c.JSON(http.StatusNotFound, gin.H{"error": "verification not found"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to load verification"})
		return
	}
	c.JSON(http.StatusOK, toResponse(v))
}

// AdminDocument streams a specific submission's document (side=front|back)
// to the admin for review.
func (h *Handler) AdminDocument(c *gin.Context) {
	id, err := uuid.Parse(c.Param("id"))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid id"})
		return
	}
	v, err := h.service.Get(c.Request.Context(), id)
	if err != nil {
		if errors.Is(err, ErrNotFound) {
			c.JSON(http.StatusNotFound, gin.H{"error": "verification not found"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to load verification"})
		return
	}
	h.serveDocument(c, v)
}

func (h *Handler) serveDocument(c *gin.Context, v *CustomerVerification) {
	path, err := h.service.DocumentPath(v, c.Param("side"))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.File(path)
}

type reviewRequest struct {
	Status    string `json:"status" binding:"required"`
	AdminNote string `json:"admin_note"`
}

func (h *Handler) Review(c *gin.Context) {
	id, err := uuid.Parse(c.Param("id"))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid id"})
		return
	}
	var req reviewRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "validation error", "details": err.Error()})
		return
	}
	if !ValidStatuses[req.Status] {
		c.JSON(http.StatusBadRequest, gin.H{"error": "status must be one of: pending, approved, rejected"})
		return
	}
	v, err := h.service.Review(c.Request.Context(), id, req.Status, req.AdminNote)
	if err != nil {
		if errors.Is(err, ErrNotFound) {
			c.JSON(http.StatusNotFound, gin.H{"error": "verification not found"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to review verification"})
		return
	}
	c.JSON(http.StatusOK, toResponse(v))
}