package handler

import (
	"context"
	"eslogad-be/internal/appcontext"
	"net/http"
	"strconv"

	"eslogad-be/internal/contract"

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

type LetterService interface {
	CreateIncomingLetter(ctx context.Context, req *contract.CreateIncomingLetterRequest) (*contract.IncomingLetterResponse, error)
	GetIncomingLetterByID(ctx context.Context, id uuid.UUID) (*contract.IncomingLetterResponse, error)
	ListIncomingLetters(ctx context.Context, req *contract.ListIncomingLettersRequest) (*contract.ListIncomingLettersResponse, error)
	UpdateIncomingLetter(ctx context.Context, id uuid.UUID, req *contract.UpdateIncomingLetterRequest) (*contract.IncomingLetterResponse, error)
	SoftDeleteIncomingLetter(ctx context.Context, id uuid.UUID) error

	CreateDispositions(ctx context.Context, req *contract.CreateLetterDispositionRequest) (*contract.ListDispositionsResponse, error)
	GetEnhancedDispositionsByLetter(ctx context.Context, letterID uuid.UUID) (*contract.ListEnhancedDispositionsResponse, error)

	CreateDiscussion(ctx context.Context, letterID uuid.UUID, req *contract.CreateLetterDiscussionRequest) (*contract.LetterDiscussionResponse, error)
	UpdateDiscussion(ctx context.Context, letterID uuid.UUID, discussionID uuid.UUID, req *contract.UpdateLetterDiscussionRequest) (*contract.LetterDiscussionResponse, error)
}

type LetterHandler struct {
	svc LetterService
}

func NewLetterHandler(svc LetterService) *LetterHandler {
	return &LetterHandler{svc: svc}
}

// Helper functions for common patterns
func (h *LetterHandler) parseUUID(c *gin.Context, param string) (uuid.UUID, bool) {
	id, err := uuid.Parse(c.Param(param))
	if err != nil {
		h.respondError(c, http.StatusBadRequest, "invalid "+param)
		return uuid.Nil, false
	}
	return id, true
}

func (h *LetterHandler) bindJSON(c *gin.Context, req interface{}) bool {
	if err := c.ShouldBindJSON(req); err != nil {
		h.respondError(c, http.StatusBadRequest, "invalid request body")
		return false
	}
	return true
}

func (h *LetterHandler) bindQuery(c *gin.Context, req interface{}) bool {
	if err := c.ShouldBindQuery(req); err != nil {
		h.respondError(c, http.StatusBadRequest, "invalid query parameters")
		return false
	}
	return true
}

func (h *LetterHandler) respondError(c *gin.Context, code int, message string) {
	c.JSON(code, &contract.ErrorResponse{
		Error: message,
		Code:  code,
	})
}

func (h *LetterHandler) respondSuccess(c *gin.Context, code int, data interface{}) {
	c.JSON(code, contract.BuildSuccessResponse(data))
}

func (h *LetterHandler) handleServiceError(c *gin.Context, err error) {
	if err != nil {
		h.respondError(c, http.StatusInternalServerError, err.Error())
	}
}

func (h *LetterHandler) CreateIncomingLetter(c *gin.Context) {
	var req contract.CreateIncomingLetterRequest
	if !h.bindJSON(c, &req) {
		return
	}

	resp, err := h.svc.CreateIncomingLetter(c.Request.Context(), &req)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusCreated, resp)
}

func (h *LetterHandler) GetIncomingLetter(c *gin.Context) {
	id, ok := h.parseUUID(c, "id")
	if !ok {
		return
	}

	resp, err := h.svc.GetIncomingLetterByID(c.Request.Context(), id)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusOK, resp)
}

func (h *LetterHandler) ListIncomingLetters(c *gin.Context) {
	req := h.parseListRequest(c)

	resp, err := h.svc.ListIncomingLetters(c.Request.Context(), req)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusOK, resp)
}

func (h *LetterHandler) parseListRequest(c *gin.Context) *contract.ListIncomingLettersRequest {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	limit, _ := strconv.Atoi(c.DefaultQuery("limit", "10"))

	// Ensure valid pagination values
	if page < 1 {
		page = 1
	}
	if limit < 1 {
		limit = 10
	}
	if limit > 100 {
		limit = 100
	}

	req := &contract.ListIncomingLettersRequest{
		Page:  page,
		Limit: limit,
	}

	// Handle optional query parameters
	if status := c.Query("status"); status != "" {
		req.Status = &status
	}
	if query := c.Query("q"); query != "" {
		req.Query = &query
	}

	return req
}

func (h *LetterHandler) UpdateIncomingLetter(c *gin.Context) {
	id, ok := h.parseUUID(c, "id")
	if !ok {
		return
	}

	var req contract.UpdateIncomingLetterRequest
	if !h.bindJSON(c, &req) {
		return
	}

	resp, err := h.svc.UpdateIncomingLetter(c.Request.Context(), id, &req)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusOK, resp)
}

func (h *LetterHandler) DeleteIncomingLetter(c *gin.Context) {
	id, ok := h.parseUUID(c, "id")
	if !ok {
		return
	}

	if err := h.svc.SoftDeleteIncomingLetter(c.Request.Context(), id); err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusOK, &contract.SuccessResponse{
		Message: "Letter deleted successfully",
	})
}

func (h *LetterHandler) CreateDispositions(c *gin.Context) {
	var req contract.CreateLetterDispositionRequest
	if !h.bindJSON(c, &req) {
		return
	}

	// Extract department ID from context
	appCtx := appcontext.FromGinContext(c.Request.Context())
	req.FromDepartment = appCtx.DepartmentID

	resp, err := h.svc.CreateDispositions(c.Request.Context(), &req)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusCreated, resp)
}

func (h *LetterHandler) GetEnhancedDispositionsByLetter(c *gin.Context) {
	letterID, ok := h.parseUUID(c, "letter_id")
	if !ok {
		return
	}

	resp, err := h.svc.GetEnhancedDispositionsByLetter(c.Request.Context(), letterID)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusOK, resp)
}

func (h *LetterHandler) CreateDiscussion(c *gin.Context) {
	letterID, ok := h.parseUUID(c, "letter_id")
	if !ok {
		return
	}

	var req contract.CreateLetterDiscussionRequest
	if !h.bindJSON(c, &req) {
		return
	}

	resp, err := h.svc.CreateDiscussion(c.Request.Context(), letterID, &req)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusCreated, resp)
}

func (h *LetterHandler) UpdateDiscussion(c *gin.Context) {
	letterID, ok := h.parseUUID(c, "letter_id")
	if !ok {
		return
	}

	discussionID, ok := h.parseUUID(c, "discussion_id")
	if !ok {
		return
	}

	var req contract.UpdateLetterDiscussionRequest
	if !h.bindJSON(c, &req) {
		return
	}

	resp, err := h.svc.UpdateDiscussion(c.Request.Context(), letterID, discussionID, &req)
	if err != nil {
		h.handleServiceError(c, err)
		return
	}

	h.respondSuccess(c, http.StatusOK, resp)
}