package news

import (
	"dk/internal/store"
	"fmt"
	"sort"
	"strings"
	"sync"
	"time"
)

// News represents a news post in the game
type News struct {
	ID      int    `json:"id"`
	Author  int    `json:"author"`
	Posted  int64  `json:"posted"`
	Content string `json:"content"`
}

func (n *News) Save() error {
	newsStore := GetStore()
	newsStore.UpdateNews(n)
	return nil
}

func (n *News) Delete() error {
	newsStore := GetStore()
	newsStore.RemoveNews(n.ID)
	return nil
}

// Creates a new News with sensible defaults
func New() *News {
	return &News{
		Author:  0,                 // No author by default
		Posted:  time.Now().Unix(), // Current time
		Content: "",                // Empty content
	}
}

// Validate checks if news has valid values
func (n *News) Validate() error {
	if n.Posted < 0 {
		return fmt.Errorf("news Posted timestamp cannot be negative")
	}
	if strings.TrimSpace(n.Content) == "" {
		return fmt.Errorf("news Content cannot be empty")
	}
	return nil
}

// NewsStore provides in-memory storage with O(1) lookups and news-specific indices
type NewsStore struct {
	*store.BaseStore[News]               // Embedded generic store
	byAuthor               map[int][]int // Author -> []ID
	allByPosted            []int         // All IDs sorted by posted DESC, id DESC
	mu                     sync.RWMutex  // Protects indices
}

// Global in-memory store
var newsStore *NewsStore
var storeOnce sync.Once

// Initialize the in-memory store
func initStore() {
	newsStore = &NewsStore{
		BaseStore:   store.NewBaseStore[News](),
		byAuthor:    make(map[int][]int),
		allByPosted: make([]int, 0),
	}
}

// GetStore returns the global news store
func GetStore() *NewsStore {
	storeOnce.Do(initStore)
	return newsStore
}

// AddNews adds a news post to the in-memory store and updates all indices
func (ns *NewsStore) AddNews(news *News) {
	ns.mu.Lock()
	defer ns.mu.Unlock()

	// Validate news
	if err := news.Validate(); err != nil {
		return
	}

	// Add to base store
	ns.Add(news.ID, news)

	// Rebuild indices
	ns.rebuildIndicesUnsafe()
}

// RemoveNews removes a news post from the store and updates indices
func (ns *NewsStore) RemoveNews(id int) {
	ns.mu.Lock()
	defer ns.mu.Unlock()

	// Remove from base store
	ns.Remove(id)

	// Rebuild indices
	ns.rebuildIndicesUnsafe()
}

// UpdateNews updates a news post efficiently
func (ns *NewsStore) UpdateNews(news *News) {
	ns.mu.Lock()
	defer ns.mu.Unlock()

	// Validate news
	if err := news.Validate(); err != nil {
		return
	}

	// Update base store
	ns.Add(news.ID, news)

	// Rebuild indices
	ns.rebuildIndicesUnsafe()
}

// LoadData loads news data from JSON file, or starts with empty store
func LoadData(dataPath string) error {
	ns := GetStore()

	// Load from base store, which handles JSON loading
	if err := ns.BaseStore.LoadData(dataPath); err != nil {
		return err
	}

	// Rebuild indices from loaded data
	ns.rebuildIndices()
	return nil
}

// SaveData saves news data to JSON file
func SaveData(dataPath string) error {
	ns := GetStore()
	return ns.BaseStore.SaveData(dataPath)
}

// rebuildIndicesUnsafe rebuilds all indices from base store data (caller must hold lock)
func (ns *NewsStore) rebuildIndicesUnsafe() {
	// Clear indices
	ns.byAuthor = make(map[int][]int)
	ns.allByPosted = make([]int, 0)

	// Collect all news and build indices
	allNews := ns.GetAll()

	for id, news := range allNews {
		// Author index
		ns.byAuthor[news.Author] = append(ns.byAuthor[news.Author], id)

		// All IDs
		ns.allByPosted = append(ns.allByPosted, id)
	}

	// Sort allByPosted by posted DESC, then ID DESC
	sort.Slice(ns.allByPosted, func(i, j int) bool {
		newsI, _ := ns.GetByID(ns.allByPosted[i])
		newsJ, _ := ns.GetByID(ns.allByPosted[j])
		if newsI.Posted != newsJ.Posted {
			return newsI.Posted > newsJ.Posted // DESC
		}
		return ns.allByPosted[i] > ns.allByPosted[j] // DESC
	})

	// Sort author indices by posted DESC, then ID DESC
	for author := range ns.byAuthor {
		sort.Slice(ns.byAuthor[author], func(i, j int) bool {
			newsI, _ := ns.GetByID(ns.byAuthor[author][i])
			newsJ, _ := ns.GetByID(ns.byAuthor[author][j])
			if newsI.Posted != newsJ.Posted {
				return newsI.Posted > newsJ.Posted // DESC
			}
			return ns.byAuthor[author][i] > ns.byAuthor[author][j] // DESC
		})
	}
}

// rebuildIndices rebuilds all news-specific indices from base store data
func (ns *NewsStore) rebuildIndices() {
	ns.mu.Lock()
	defer ns.mu.Unlock()
	ns.rebuildIndicesUnsafe()
}

// Retrieves a news post by ID
func Find(id int) (*News, error) {
	ns := GetStore()
	news, exists := ns.GetByID(id)
	if !exists {
		return nil, fmt.Errorf("news with ID %d not found", id)
	}
	return news, nil
}

// Retrieves all news posts ordered by posted date (newest first)
func All() ([]*News, error) {
	ns := GetStore()
	ns.mu.RLock()
	defer ns.mu.RUnlock()

	result := make([]*News, 0, len(ns.allByPosted))
	for _, id := range ns.allByPosted {
		if news, exists := ns.GetByID(id); exists {
			result = append(result, news)
		}
	}
	return result, nil
}

// Retrieves news posts by a specific author
func ByAuthor(authorID int) ([]*News, error) {
	ns := GetStore()
	ns.mu.RLock()
	defer ns.mu.RUnlock()

	ids, exists := ns.byAuthor[authorID]
	if !exists {
		return []*News{}, nil
	}

	result := make([]*News, 0, len(ids))
	for _, id := range ids {
		if news, exists := ns.GetByID(id); exists {
			result = append(result, news)
		}
	}
	return result, nil
}

// Retrieves the most recent news posts (limited by count)
func Recent(limit int) ([]*News, error) {
	ns := GetStore()
	ns.mu.RLock()
	defer ns.mu.RUnlock()

	if limit > len(ns.allByPosted) {
		limit = len(ns.allByPosted)
	}

	result := make([]*News, 0, limit)
	for i := 0; i < limit; i++ {
		if news, exists := ns.GetByID(ns.allByPosted[i]); exists {
			result = append(result, news)
		}
	}
	return result, nil
}

// Retrieves news posts since a specific timestamp
func Since(since int64) ([]*News, error) {
	ns := GetStore()
	ns.mu.RLock()
	defer ns.mu.RUnlock()

	var result []*News
	for _, id := range ns.allByPosted {
		if news, exists := ns.GetByID(id); exists && news.Posted >= since {
			result = append(result, news)
		}
	}
	return result, nil
}

// Retrieves news posts between two timestamps (inclusive)
func Between(start, end int64) ([]*News, error) {
	ns := GetStore()
	ns.mu.RLock()
	defer ns.mu.RUnlock()

	var result []*News
	for _, id := range ns.allByPosted {
		if news, exists := ns.GetByID(id); exists && news.Posted >= start && news.Posted <= end {
			result = append(result, news)
		}
	}
	return result, nil
}

// Retrieves news posts containing the search term in content
func Search(term string) ([]*News, error) {
	ns := GetStore()
	ns.mu.RLock()
	defer ns.mu.RUnlock()

	var result []*News
	lowerTerm := strings.ToLower(term)

	for _, id := range ns.allByPosted {
		if news, exists := ns.GetByID(id); exists {
			if strings.Contains(strings.ToLower(news.Content), lowerTerm) {
				result = append(result, news)
			}
		}
	}
	return result, nil
}

// Saves a new news post to the in-memory store and sets the ID
func (n *News) Insert() error {
	ns := GetStore()

	// Validate before insertion
	if err := n.Validate(); err != nil {
		return fmt.Errorf("validation failed: %w", err)
	}

	// Assign new ID if not set
	if n.ID == 0 {
		n.ID = ns.GetNextID()
	}

	// Add to store
	ns.AddNews(n)
	return nil
}

// Returns the posted timestamp as a time.Time
func (n *News) PostedTime() time.Time {
	return time.Unix(n.Posted, 0)
}

// Sets the posted timestamp from a time.Time
func (n *News) SetPostedTime(t time.Time) {
	n.Posted = t.Unix()
}

// Returns true if the news post was made within the last 24 hours
func (n *News) IsRecent() bool {
	return time.Since(n.PostedTime()) < 24*time.Hour
}

// Returns how long ago the news post was made
func (n *News) Age() time.Duration {
	return time.Since(n.PostedTime())
}

// Converts a time.Time to a human-readable date string
func (n *News) ReadableTime() string {
	return n.PostedTime().Format("Jan 2, 2006 3:04 PM")
}

// Returns true if the given user ID is the author of this news post
func (n *News) IsAuthor(userID int) bool {
	return n.Author == userID
}

// Returns a truncated version of the content for previews
func (n *News) Preview(maxLength int) string {
	if len(n.Content) <= maxLength {
		return n.Content
	}

	if maxLength < 3 {
		return n.Content[:maxLength]
	}

	return n.Content[:maxLength-3] + "..."
}

// Returns the number of words in the content
func (n *News) WordCount() int {
	if n.Content == "" {
		return 0
	}

	// Simple word count by splitting on spaces
	words := 0
	inWord := false

	for _, char := range n.Content {
		if char == ' ' || char == '\t' || char == '\n' || char == '\r' {
			if inWord {
				words++
				inWord = false
			}
		} else {
			inWord = true
		}
	}

	if inWord {
		words++
	}

	return words
}

// Returns the character length of the content
func (n *News) Length() int {
	return len(n.Content)
}

// Returns true if the content contains the given term (case-insensitive)
func (n *News) Contains(term string) bool {
	return strings.Contains(strings.ToLower(n.Content), strings.ToLower(term))
}

// Returns true if the content is empty or whitespace-only
func (n *News) IsEmpty() bool {
	return strings.TrimSpace(n.Content) == ""
}