package api

import (
	"context"
	"fmt"
	"log"
	"net/url"
	"sort"
	"sync"
	"time"

	"task-dashboard/internal/models"
)

const trelloBaseURL = "https://api.trello.com/1"

// TrelloClient handles interactions with the Trello API
type TrelloClient struct {
	BaseClient
	apiKey string
	token  string
}

// NewTrelloClient creates a new Trello API client
func NewTrelloClient(apiKey, token string) *TrelloClient {
	return &TrelloClient{
		BaseClient: NewBaseClient(trelloBaseURL),
		apiKey:     apiKey,
		token:      token,
	}
}

func (c *TrelloClient) authParams() url.Values {
	params := url.Values{}
	params.Set("key", c.apiKey)
	params.Set("token", c.token)
	return params
}

// trelloBoardResponse represents a board from the API
type trelloBoardResponse struct {
	ID   string `json:"id"`
	Name string `json:"name"`
}

// trelloCardResponse represents a card from the API
type trelloCardResponse struct {
	ID      string  `json:"id"`
	Name    string  `json:"name"`
	IDList  string  `json:"idList"`
	Due     *string `json:"due"`
	URL     string  `json:"url"`
	Desc    string  `json:"desc"`
	IDBoard string  `json:"idBoard"`
}

// trelloListResponse represents a list from the API
type trelloListResponse struct {
	ID   string `json:"id"`
	Name string `json:"name"`
}

// GetBoards fetches all boards for the authenticated user
func (c *TrelloClient) GetBoards(ctx context.Context) ([]models.Board, error) {
	params := c.authParams()
	params.Set("filter", "open")
	params.Set("fields", "id,name")

	var apiBoards []trelloBoardResponse
	if err := c.Get(ctx, "/members/me/boards?"+params.Encode(), nil, &apiBoards); err != nil {
		return nil, fmt.Errorf("failed to fetch boards: %w", err)
	}

	boards := make([]models.Board, 0, len(apiBoards))
	for _, apiBoard := range apiBoards {
		boards = append(boards, models.Board{
			ID:    apiBoard.ID,
			Name:  apiBoard.Name,
			Cards: []models.Card{},
		})
	}

	return boards, nil
}

// GetCards fetches all cards for a specific board
func (c *TrelloClient) GetCards(ctx context.Context, boardID string) ([]models.Card, error) {
	params := c.authParams()
	params.Set("filter", "open")
	params.Set("fields", "id,name,idList,due,url,idBoard")

	var apiCards []trelloCardResponse
	path := fmt.Sprintf("/boards/%s/cards?%s", boardID, params.Encode())
	if err := c.Get(ctx, path, nil, &apiCards); err != nil {
		return nil, fmt.Errorf("failed to fetch cards: %w", err)
	}

	if len(apiCards) == 0 {
		log.Printf("Trello GetCards: board %s returned 0 cards (may have only archived cards)", boardID)
	} else {
		log.Printf("Trello GetCards: board %s returned %d cards", boardID, len(apiCards))
	}

	// Fetch lists to get list names
	lists, err := c.getLists(ctx, boardID)
	listMap := make(map[string]string)
	if err != nil {
		log.Printf("Warning: failed to fetch lists for board %s: %v", boardID, err)
	} else {
		for _, list := range lists {
			listMap[list.ID] = list.Name
		}
	}

	cards := make([]models.Card, 0, len(apiCards))
	for _, apiCard := range apiCards {
		card := models.Card{
			ID:       apiCard.ID,
			Name:     apiCard.Name,
			ListID:   apiCard.IDList,
			ListName: listMap[apiCard.IDList],
			URL:      apiCard.URL,
		}

		if apiCard.Due != nil && *apiCard.Due != "" {
			if dueDate, err := time.Parse(time.RFC3339, *apiCard.Due); err == nil {
				card.DueDate = &dueDate
			}
		}

		cards = append(cards, card)
	}

	return cards, nil
}

// getLists fetches lists for a board
func (c *TrelloClient) getLists(ctx context.Context, boardID string) ([]models.List, error) {
	params := c.authParams()
	params.Set("fields", "id,name")

	var apiLists []trelloListResponse
	path := fmt.Sprintf("/boards/%s/lists?%s", boardID, params.Encode())
	if err := c.Get(ctx, path, nil, &apiLists); err != nil {
		return nil, fmt.Errorf("failed to fetch lists: %w", err)
	}

	lists := make([]models.List, 0, len(apiLists))
	for _, apiList := range apiLists {
		lists = append(lists, models.List{
			ID:   apiList.ID,
			Name: apiList.Name,
		})
	}

	return lists, nil
}

// GetLists fetches lists for a specific board
func (c *TrelloClient) GetLists(ctx context.Context, boardID string) ([]models.List, error) {
	return c.getLists(ctx, boardID)
}

// GetBoardsWithCards fetches all boards and their cards concurrently
func (c *TrelloClient) GetBoardsWithCards(ctx context.Context) ([]models.Board, error) {
	boards, err := c.GetBoards(ctx)
	if err != nil {
		return nil, err
	}

	var wg sync.WaitGroup
	sem := make(chan struct{}, 5) // Limit to 5 concurrent requests

	for i := range boards {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()

			sem <- struct{}{}
			defer func() { <-sem }()

			cards, err := c.GetCards(ctx, boards[i].ID)
			if err != nil {
				log.Printf("Error fetching cards for board %s (%s): %v", boards[i].Name, boards[i].ID, err)
			} else {
				for j := range cards {
					cards[j].BoardName = boards[i].Name
				}
				boards[i].Cards = cards
			}

			lists, err := c.getLists(ctx, boards[i].ID)
			if err != nil {
				log.Printf("Error fetching lists for board %s: %v", boards[i].Name, err)
			} else {
				boards[i].Lists = lists
			}
		}(i)
	}

	wg.Wait()

	// Sort boards: Non-empty boards first, newest card activity, then alphabetical
	sort.Slice(boards, func(i, j int) bool {
		hasCardsI := len(boards[i].Cards) > 0
		hasCardsJ := len(boards[j].Cards) > 0

		if hasCardsI != hasCardsJ {
			return hasCardsI
		}

		if hasCardsI && hasCardsJ {
			maxIDI := ""
			for _, card := range boards[i].Cards {
				if maxIDI == "" || card.ID > maxIDI {
					maxIDI = card.ID
				}
			}

			maxIDJ := ""
			for _, card := range boards[j].Cards {
				if maxIDJ == "" || card.ID > maxIDJ {
					maxIDJ = card.ID
				}
			}

			if maxIDI != maxIDJ {
				return maxIDI > maxIDJ
			}
		}

		return boards[i].Name < boards[j].Name
	})

	return boards, nil
}

// CreateCard creates a new card in the specified list
func (c *TrelloClient) CreateCard(ctx context.Context, listID, name, description string, dueDate *time.Time) (*models.Card, error) {
	data := c.authParams()
	data.Set("idList", listID)
	data.Set("name", name)
	if description != "" {
		data.Set("desc", description)
	}
	if dueDate != nil {
		data.Set("due", dueDate.Format(time.RFC3339))
	}

	var apiCard trelloCardResponse
	if err := c.PostForm(ctx, "/cards", nil, data.Encode(), &apiCard); err != nil {
		return nil, fmt.Errorf("failed to create card: %w", err)
	}

	card := &models.Card{
		ID:     apiCard.ID,
		Name:   apiCard.Name,
		ListID: apiCard.IDList,
		URL:    apiCard.URL,
	}

	if apiCard.Due != nil && *apiCard.Due != "" {
		if parsedDate, err := time.Parse(time.RFC3339, *apiCard.Due); err == nil {
			card.DueDate = &parsedDate
		}
	}

	return card, nil
}

// UpdateCard updates a card with the specified changes
func (c *TrelloClient) UpdateCard(ctx context.Context, cardID string, updates map[string]interface{}) error {
	data := c.authParams()
	for key, value := range updates {
		data.Set(key, fmt.Sprintf("%v", value))
	}

	path := fmt.Sprintf("/cards/%s", cardID)
	if err := c.Put(ctx, path, nil, data.Encode(), nil); err != nil {
		return fmt.Errorf("failed to update card: %w", err)
	}

	return nil
}