package handlers

import (
	"encoding/json"
	"log"
	"net/http"
	"time"

	"task-dashboard/internal/models"
)

// AISnapshotResponse matches the exact format requested by the user
type AISnapshotResponse struct {
	GeneratedAt   string                  `json:"generated_at"`
	Tasks         AITasksSection          `json:"tasks"`
	Meals         AIMealsSection          `json:"meals"`
	Notes         AINotesSection          `json:"notes"`
	TrelloBoards  []AITrelloBoard         `json:"trello_boards,omitempty"`
}

type AITasksSection struct {
	Today      []AITask `json:"today"`
	Overdue    []AITask `json:"overdue"`
	Next7Days  []AITask `json:"next_7_days"`
}

type AITask struct {
	ID        string  `json:"id"`
	Content   string  `json:"content"`
	Priority  int     `json:"priority"`
	Due       *string `json:"due,omitempty"`
	Project   string  `json:"project"`
	Completed bool    `json:"completed"`
}

type AIMealsSection struct {
	Today     AIDayMeals   `json:"today"`
	Next7Days []AIDayMeals `json:"next_7_days"`
}

type AIDayMeals struct {
	Date      string `json:"date"`
	Breakfast string `json:"breakfast,omitempty"`
	Lunch     string `json:"lunch,omitempty"`
	Dinner    string `json:"dinner,omitempty"`
	Snack     string `json:"snack,omitempty"`
}

type AINotesSection struct {
	Recent []AINote `json:"recent"`
}

type AINote struct {
	Title    string `json:"title"`
	Modified string `json:"modified"`
	Preview  string `json:"preview"`
	Path     string `json:"path"`
}

type AITrelloBoard struct {
	ID    string      `json:"id"`
	Name  string      `json:"name"`
	Cards []AITrelloCard `json:"cards"`
}

type AITrelloCard struct {
	ID      string  `json:"id"`
	Name    string  `json:"name"`
	List    string  `json:"list"`
	Due     *string `json:"due,omitempty"`
	URL     string  `json:"url"`
}

// HandleAISnapshot returns a complete dashboard snapshot optimized for AI consumption
func (h *Handler) HandleAISnapshot(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	// Fetch all data (with caching)
	data, err := h.aggregateData(ctx, false)
	if err != nil {
		respondJSON(w, http.StatusInternalServerError, map[string]string{
			"error":   "server_error",
			"message": "Failed to fetch dashboard data",
		})
		log.Printf("AI snapshot error: %v", err)
		return
	}

	// Build AI-optimized response
	response := AISnapshotResponse{
		GeneratedAt:  time.Now().UTC().Format(time.RFC3339),
		Tasks:        buildAITasksSection(data.Tasks),
		Meals:        buildAIMealsSection(data.Meals),
		Notes:        buildAINotesSection(data.Notes),
		TrelloBoards: buildAITrelloBoardsSection(data.Boards),
	}

	respondJSON(w, http.StatusOK, response)
}

// buildAITasksSection organizes tasks by time window
func buildAITasksSection(tasks []models.Task) AITasksSection {
	now := time.Now()
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	next7Days := today.AddDate(0, 0, 7)

	section := AITasksSection{
		Today:     []AITask{},
		Overdue:   []AITask{},
		Next7Days: []AITask{},
	}

	for _, task := range tasks {
		if task.Completed {
			continue // Skip completed tasks
		}

		aiTask := AITask{
			ID:        task.ID,
			Content:   task.Content,
			Priority:  task.Priority,
			Project:   task.ProjectName,
			Completed: task.Completed,
		}

		if task.DueDate != nil {
			dueStr := task.DueDate.UTC().Format(time.RFC3339)
			aiTask.Due = &dueStr

			taskDay := time.Date(task.DueDate.Year(), task.DueDate.Month(), task.DueDate.Day(), 0, 0, 0, 0, task.DueDate.Location())

			if taskDay.Before(today) {
				section.Overdue = append(section.Overdue, aiTask)
			} else if taskDay.Equal(today) {
				section.Today = append(section.Today, aiTask)
			} else if taskDay.Before(next7Days) {
				section.Next7Days = append(section.Next7Days, aiTask)
			}
		}
	}

	return section
}

// buildAIMealsSection organizes meals by day
func buildAIMealsSection(meals []models.Meal) AIMealsSection {
	now := time.Now()
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	next7Days := today.AddDate(0, 0, 7)

	section := AIMealsSection{
		Today:     AIDayMeals{Date: today.Format("2006-01-02")},
		Next7Days: []AIDayMeals{},
	}

	// Group meals by date
	mealsByDate := make(map[string]*AIDayMeals)

	for _, meal := range meals {
		mealDay := time.Date(meal.Date.Year(), meal.Date.Month(), meal.Date.Day(), 0, 0, 0, 0, meal.Date.Location())

		if mealDay.Before(today) || mealDay.After(next7Days) {
			continue // Skip meals outside our window
		}

		dateStr := mealDay.Format("2006-01-02")

		if _, exists := mealsByDate[dateStr]; !exists {
			mealsByDate[dateStr] = &AIDayMeals{Date: dateStr}
		}

		dayMeals := mealsByDate[dateStr]

		switch meal.MealType {
		case "breakfast":
			dayMeals.Breakfast = meal.RecipeName
		case "lunch":
			dayMeals.Lunch = meal.RecipeName
		case "dinner":
			dayMeals.Dinner = meal.RecipeName
		case "snack":
			dayMeals.Snack = meal.RecipeName
		}
	}

	// Assign today's meals
	if todayMeals, exists := mealsByDate[today.Format("2006-01-02")]; exists {
		section.Today = *todayMeals
	}

	// Collect next 7 days (excluding today)
	for i := 1; i <= 7; i++ {
		day := today.AddDate(0, 0, i)
		dateStr := day.Format("2006-01-02")
		if dayMeals, exists := mealsByDate[dateStr]; exists {
			section.Next7Days = append(section.Next7Days, *dayMeals)
		}
	}

	return section
}

// buildAINotesSection returns the 10 most recent notes with previews
func buildAINotesSection(notes []models.Note) AINotesSection {
	section := AINotesSection{
		Recent: []AINote{},
	}

	// Limit to 10 most recent
	limit := 10
	if len(notes) < limit {
		limit = len(notes)
	}

	for i := 0; i < limit; i++ {
		note := notes[i]

		// Limit preview to 150 chars
		preview := note.Content
		if len(preview) > 150 {
			preview = preview[:150] + "..."
		}

		section.Recent = append(section.Recent, AINote{
			Title:    note.Title,
			Modified: note.Modified.UTC().Format(time.RFC3339),
			Preview:  preview,
			Path:     note.Path,
		})
	}

	return section
}

// buildAITrelloBoardsSection formats Trello boards for AI
func buildAITrelloBoardsSection(boards []models.Board) []AITrelloBoard {
	aiBoards := []AITrelloBoard{}

	for _, board := range boards {
		aiBoard := AITrelloBoard{
			ID:    board.ID,
			Name:  board.Name,
			Cards: []AITrelloCard{},
		}

		for _, card := range board.Cards {
			aiCard := AITrelloCard{
				ID:   card.ID,
				Name: card.Name,
				List: card.ListName,
				URL:  card.URL,
			}

			if card.DueDate != nil {
				dueStr := card.DueDate.UTC().Format(time.RFC3339)
				aiCard.Due = &dueStr
			}

			aiBoard.Cards = append(aiBoard.Cards, aiCard)
		}

		aiBoards = append(aiBoards, aiBoard)
	}

	return aiBoards
}

// respondJSON sends a JSON response
func respondJSON(w http.ResponseWriter, status int, data interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(data)
}