import Foundation
import SwiftUI

@MainActor
final class FavoritesStore: ObservableObject {
    @Published private(set) var items: [MediaItem] = []

    private var profileId: String?
    private let defaults = UserDefaults.standard

    private func cacheKey(for profileId: String) -> String {
        "vmc.tv.favorites.cache.\(profileId)"
    }

    func bind(profileId: String?) {
        self.profileId = profileId
        guard let profileId, !profileId.isEmpty else {
            items = []
            return
        }
        items = loadCache(profileId: profileId)
    }

    func contains(type: String, id: String) -> Bool {
        let want = normalizedType(type)
        return items.contains {
            $0.id == id && normalizedType($0.type) == want
        }
    }

    private func normalizedType(_ type: String) -> String {
        let t = type.lowercased()
        return (t == "series" || t == "show") ? "series" : "movie"
    }

    func replaceAll(_ next: [MediaItem]) {
        items = next
        persistCache()
    }

    @discardableResult
    func toggle(
        type: String,
        id: String,
        title: String,
        year: Int?,
        posterUrl: String?,
        backdropUrl: String?,
        logoUrl: String?,
        api: ApiClient
    ) async -> Bool {
        let normalized = normalizedType(type)
        let wasOn = contains(type: normalized, id: id)

        if wasOn {
            items.removeAll { $0.id == id && normalizedType($0.type) == normalized }
        } else {
            let item = MediaItem(
                type: normalized.uppercased() == "SERIES" ? "SERIES" : "MOVIE",
                id: id,
                title: title,
                subtitle: nil,
                year: year,
                posterUrl: posterUrl,
                backdropUrl: backdropUrl,
                logoUrl: logoUrl,
                mediaFileId: nil,
                seriesId: nil,
                positionMs: nil,
                durationMs: nil,
                progressId: nil,
                badge: nil
            )
            items.insert(item, at: 0)
        }
        persistCache()

        do {
            let result = try await api.toggleFavorite(type: normalized, id: id)
            if let remote = result.items {
                replaceAll(remote)
            } else {
                await refresh(using: api)
            }
            return result.favorited
        } catch {
            if wasOn {
                let item = MediaItem(
                    type: normalized.uppercased() == "SERIES" ? "SERIES" : "MOVIE",
                    id: id,
                    title: title,
                    subtitle: nil,
                    year: year,
                    posterUrl: posterUrl,
                    backdropUrl: backdropUrl,
                    logoUrl: logoUrl,
                    mediaFileId: nil,
                    seriesId: nil,
                    positionMs: nil,
                    durationMs: nil,
                    progressId: nil,
                    badge: nil
                )
                items.insert(item, at: 0)
            } else {
                items.removeAll { $0.id == id && normalizedType($0.type) == normalized }
            }
            persistCache()
            return wasOn
        }
    }

    func refresh(using api: ApiClient) async {
        guard let profileId, !profileId.isEmpty else {
            items = []
            return
        }
        do {
            let remote = try await api.listFavorites()
            replaceAll(remote)
        } catch {
            if items.isEmpty {
                items = loadCache(profileId: profileId)
            }
        }
    }

    var mediaItems: [MediaItem] { items }

    private func loadCache(profileId: String) -> [MediaItem] {
        guard let data = defaults.data(forKey: cacheKey(for: profileId)),
              let decoded = try? JSONDecoder().decode([MediaItem].self, from: data)
        else { return [] }
        return decoded
    }

    private func persistCache() {
        guard let profileId, !profileId.isEmpty else { return }
        if let data = try? JSONEncoder().encode(items) {
            defaults.set(data, forKey: cacheKey(for: profileId))
        }
    }
}