package handlers

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

	"github.com/go-chi/chi/v5"

	"task-dashboard/internal/models"
	"task-dashboard/internal/store"
)

// BuildBucketSummaries returns every maintenance bucket with its full pool
// (dormant and active items both). Backs the Settings page's bucket
// management section.
func BuildBucketSummaries(s *store.Store) ([]models.BucketSummary, error) {
	buckets, err := s.GetBuckets()
	if err != nil {
		return nil, err
	}
	summaries := make([]models.BucketSummary, 0, len(buckets))
	for _, bucket := range buckets {
		items, err := s.GetBucketItems(bucket.ID)
		if err != nil {
			return nil, err
		}
		summaries = append(summaries, models.BucketSummary{Bucket: bucket, Items: items})
	}
	return summaries, nil
}

// HandleBucketsCreate creates a new maintenance bucket from the Settings page's form.
func (h *Handler) HandleBucketsCreate(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		JSONError(w, http.StatusBadRequest, "Failed to parse form", err)
		return
	}
	name := strings.TrimSpace(r.FormValue("name"))
	cycleDays, err1 := strconv.Atoi(r.FormValue("cycle_days"))
	pickN, err2 := strconv.Atoi(r.FormValue("pick_n"))
	if name == "" || err1 != nil || err2 != nil || cycleDays <= 0 || pickN <= 0 {
		JSONError(w, http.StatusBadRequest, "Name, a positive cycle_days, and a positive pick_n are required", nil)
		return
	}
	if _, err := h.store.CreateBucket(name, cycleDays, pickN); err != nil {
		JSONError(w, http.StatusInternalServerError, "Failed to create bucket", err)
		return
	}
	h.renderBucketsSection(w, r)
}

// HandleBucketItemAdd creates a new native task from the form's title and
// assigns it to the bucket's pool in one step -- the Settings page's
// "type a title to add to the pool" flow. To add a task that already
// exists elsewhere, use the /api/widget/buckets/{id}/items endpoint with
// its id directly (unchanged, still task_id-based).
func (h *Handler) HandleBucketItemAdd(w http.ResponseWriter, r *http.Request) {
	bucketID := chi.URLParam(r, "id")
	if err := r.ParseForm(); err != nil {
		JSONError(w, http.StatusBadRequest, "Failed to parse form", err)
		return
	}
	title := strings.TrimSpace(r.FormValue("title"))
	if title == "" {
		JSONError(w, http.StatusBadRequest, "title is required", nil)
		return
	}
	task := models.Task{ID: newID(), Content: title, Priority: 1}
	if err := h.store.CreateNativeTask(task); err != nil {
		JSONError(w, http.StatusInternalServerError, "Failed to create task", err)
		return
	}
	if err := h.store.AddBucketItem(bucketID, task.ID); err != nil {
		JSONError(w, http.StatusInternalServerError, "Failed to add task to bucket", err)
		return
	}
	h.renderBucketsSection(w, r)
}

// HandleBucketItemRemove clears a task's bucket membership from the
// Settings page (the task itself is left in place, just unbucketed).
func (h *Handler) HandleBucketItemRemove(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		JSONError(w, http.StatusBadRequest, "Failed to parse form", err)
		return
	}
	taskID := r.FormValue("task_id")
	if err := h.store.RemoveBucketItem(taskID); err != nil {
		if errors.Is(err, store.ErrNativeTaskNotFound) {
			JSONError(w, http.StatusNotFound, "task not found", err)
			return
		}
		JSONError(w, http.StatusInternalServerError, "Failed to remove bucket item", err)
		return
	}
	h.renderBucketsSection(w, r)
}

// HandleBucketDelete removes a bucket, returning its member tasks to being
// plain unbucketed tasks.
func (h *Handler) HandleBucketDelete(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	if err := h.store.DeleteBucket(id); err != nil {
		if errors.Is(err, store.ErrNativeTaskNotFound) {
			JSONError(w, http.StatusNotFound, "bucket not found", err)
			return
		}
		JSONError(w, http.StatusInternalServerError, "Failed to delete bucket", err)
		return
	}
	h.renderBucketsSection(w, r)
}

// renderBucketsSection re-renders the "buckets-section" partial after any
// bucket mutation, so the Settings page's htmx targets can swap in the
// fresh pool contents without a full page reload.
func (h *Handler) renderBucketsSection(w http.ResponseWriter, r *http.Request) {
	summaries, err := BuildBucketSummaries(h.store)
	if err != nil {
		JSONError(w, http.StatusInternalServerError, "Failed to load buckets", err)
		return
	}
	data := struct {
		Buckets []models.BucketSummary
	}{Buckets: summaries}
	if err := h.renderer.Render(w, "buckets-section", data); err != nil {
		JSONError(w, http.StatusInternalServerError, "Failed to render buckets", err)
	}
}