package handlers

import (
	"net/http"
	"strconv"

	"github.com/calendarapi/internal/middleware"
	"github.com/calendarapi/internal/models"
	"github.com/calendarapi/internal/service"
	"github.com/calendarapi/internal/utils"
	"github.com/go-chi/chi/v5"
)

type TaskHandler struct {
	taskSvc *service.TaskService
}

func NewTaskHandler(taskSvc *service.TaskService) *TaskHandler {
	return &TaskHandler{taskSvc: taskSvc}
}

func (h *TaskHandler) List(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())
	q := r.URL.Query()

	params := service.ListTasksParams{
		Limit: 50,
	}
	if s := q.Get("status"); s != "" {
		params.Status = &s
	}
	if p := q.Get("priority"); p != "" {
		params.Priority = &p
	}
	if pid := q.Get("project_id"); pid != "" {
		if id, err := utils.ValidateUUID(pid); err == nil {
			params.ProjectID = &id
		}
	}
	if df := q.Get("due_from"); df != "" {
		if t, err := utils.ParseTime(df); err == nil {
			params.DueFrom = &t
		}
	}
	if dt := q.Get("due_to"); dt != "" {
		if t, err := utils.ParseTime(dt); err == nil {
			params.DueTo = &t
		}
	}
	if l := q.Get("limit"); l != "" {
		if v, err := strconv.Atoi(l); err == nil {
			params.Limit = v
		}
	}
	params.Cursor = q.Get("cursor")

	tasks, cursor, err := h.taskSvc.List(r.Context(), userID, params)
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	limit := int(utils.ClampLimit(params.Limit))
	page := models.PageInfo{Limit: limit}
	if cursor != nil {
		page.NextCursor = cursor
	}
	utils.WriteList(w, tasks, page)
}

func (h *TaskHandler) Create(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())

	var req struct {
		Title          string  `json:"title"`
		Description    *string `json:"description"`
		Status         *string `json:"status"`
		Priority       *string `json:"priority"`
		DueDate        *string `json:"due_date"`
		ProjectID      *string `json:"project_id"`
		ParentID       *string `json:"parent_id"`
		SortOrder      *int    `json:"sort_order"`
		RecurrenceRule *string `json:"recurrence_rule"`
	}
	if err := utils.DecodeJSON(r, &req); err != nil {
		utils.WriteError(w, err)
		return
	}

	createReq := service.CreateTaskRequest{
		Title:          req.Title,
		Description:    req.Description,
		Status:         req.Status,
		Priority:       req.Priority,
		SortOrder:      req.SortOrder,
		RecurrenceRule: req.RecurrenceRule,
	}
	if req.DueDate != nil {
		if t, err := utils.ParseTime(*req.DueDate); err == nil {
			createReq.DueDate = &t
		}
	}
	if req.ProjectID != nil {
		if id, err := utils.ValidateUUID(*req.ProjectID); err == nil {
			createReq.ProjectID = &id
		}
	}
	if req.ParentID != nil {
		if id, err := utils.ValidateUUID(*req.ParentID); err == nil {
			createReq.ParentID = &id
		}
	}

	task, err := h.taskSvc.Create(r.Context(), userID, createReq)
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	utils.WriteJSON(w, http.StatusOK, map[string]interface{}{"task": task})
}

func (h *TaskHandler) Get(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())
	taskID, err := utils.ValidateUUID(chi.URLParam(r, "id"))
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	task, err := h.taskSvc.Get(r.Context(), userID, taskID)
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	utils.WriteJSON(w, http.StatusOK, map[string]interface{}{"task": task})
}

func (h *TaskHandler) Update(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())
	taskID, err := utils.ValidateUUID(chi.URLParam(r, "id"))
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	var req struct {
		Title          *string `json:"title"`
		Description    *string `json:"description"`
		Status         *string `json:"status"`
		Priority       *string `json:"priority"`
		DueDate        *string `json:"due_date"`
		ProjectID      *string `json:"project_id"`
		SortOrder      *int    `json:"sort_order"`
		RecurrenceRule *string `json:"recurrence_rule"`
	}
	if err := utils.DecodeJSON(r, &req); err != nil {
		utils.WriteError(w, err)
		return
	}

	updateReq := service.UpdateTaskRequest{
		Title:          req.Title,
		Description:    req.Description,
		Status:         req.Status,
		Priority:       req.Priority,
		SortOrder:      req.SortOrder,
		RecurrenceRule: req.RecurrenceRule,
	}
	if req.DueDate != nil {
		if t, err := utils.ParseTime(*req.DueDate); err == nil {
			updateReq.DueDate = &t
		}
	}
	if req.ProjectID != nil {
		if id, err := utils.ValidateUUID(*req.ProjectID); err == nil {
			updateReq.ProjectID = &id
		}
	}

	task, err := h.taskSvc.Update(r.Context(), userID, taskID, updateReq)
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	utils.WriteJSON(w, http.StatusOK, map[string]interface{}{"task": task})
}

func (h *TaskHandler) Delete(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())
	taskID, err := utils.ValidateUUID(chi.URLParam(r, "id"))
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	permanent := r.URL.Query().Get("permanent") == "true"

	if err := h.taskSvc.Delete(r.Context(), userID, taskID, permanent); err != nil {
		utils.WriteError(w, err)
		return
	}

	utils.WriteOK(w)
}

func (h *TaskHandler) MarkComplete(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())
	taskID, err := utils.ValidateUUID(chi.URLParam(r, "id"))
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	task, err := h.taskSvc.MarkComplete(r.Context(), userID, taskID)
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	utils.WriteJSON(w, http.StatusOK, map[string]interface{}{"task": task})
}

func (h *TaskHandler) MarkUncomplete(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())
	taskID, err := utils.ValidateUUID(chi.URLParam(r, "id"))
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	var req struct {
		Status *string `json:"status"`
	}
	_ = utils.DecodeJSON(r, &req)

	task, err := h.taskSvc.MarkUncomplete(r.Context(), userID, taskID, req.Status)
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	utils.WriteJSON(w, http.StatusOK, map[string]interface{}{"task": task})
}

func (h *TaskHandler) ListSubtasks(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.GetUserID(r.Context())
	taskID, err := utils.ValidateUUID(chi.URLParam(r, "id"))
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	tasks, err := h.taskSvc.ListSubtasks(r.Context(), userID, taskID)
	if err != nil {
		utils.WriteError(w, err)
		return
	}

	utils.WriteList(w, tasks, models.PageInfo{Limit: len(tasks)})
}