//
//  MealPlanTabView.swift
//  Nextcloud Cookbook iOS Client
//

import Foundation
import SwiftUI

struct MealPlanTabView: View {
    @EnvironmentObject var mealPlan: MealPlanManager
    @EnvironmentObject var appState: AppState
    @EnvironmentObject var groceryList: GroceryListManager

    @State private var weekOffset: Int = 0
    @State private var addRecipeDate: Date? = nil

    private var calendar: Calendar { Calendar.current }

    private var weekDates: [Date] {
        let today = calendar.startOfDay(for: Date())
        // Find start of current week (Monday)
        let weekday = calendar.component(.weekday, from: today)
        let daysToMonday = (weekday + 5) % 7
        guard let monday = calendar.date(byAdding: .day, value: -daysToMonday, to: today),
              let offsetMonday = calendar.date(byAdding: .weekOfYear, value: weekOffset, to: monday) else {
            return []
        }
        return (0..<7).compactMap { calendar.date(byAdding: .day, value: $0, to: offsetMonday) }
    }

    private var weekLabel: String {
        if weekOffset == 0 {
            return String(localized: "This Week")
        } else if weekOffset == 1 {
            return String(localized: "Next Week")
        } else if weekOffset == -1 {
            return String(localized: "Last Week")
        } else {
            return weekRangeString
        }
    }

    private var weekRangeString: String {
        guard let first = weekDates.first, let last = weekDates.last else { return "" }
        let formatter = DateFormatter()
        formatter.dateFormat = "dd.MM."
        return "\(formatter.string(from: first)) – \(formatter.string(from: last))"
    }

    var body: some View {
        NavigationStack {
            ScrollView {
                VStack(spacing: 0) {
                    weekNavigationHeader
                        .padding(.horizontal)
                        .padding(.vertical, 8)

                    ForEach(weekDates, id: \.self) { date in
                        MealPlanDayRow(
                            date: date,
                            entries: mealPlan.entries(for: date),
                            isToday: calendar.isDateInToday(date),
                            onAdd: {
                                addRecipeDate = date
                            },
                            onRemove: { entry in
                                withAnimation {
                                    mealPlan.removeRecipe(recipeId: entry.recipeId, fromDate: entry.dateString)
                                }
                            }
                        )
                    }
                }
            }
            .navigationTitle("Meal Plan")
            .navigationDestination(for: Recipe.self) { recipe in
                RecipeView(viewModel: RecipeView.ViewModel(recipe: recipe))
                    .environmentObject(appState)
                    .environmentObject(groceryList)
                    .environmentObject(mealPlan)
            }
            .sheet(item: $addRecipeDate) { date in
                RecipePickerForMealPlan(date: date)
                    .environmentObject(mealPlan)
                    .environmentObject(appState)
            }
        }
    }

    private var weekNavigationHeader: some View {
        HStack {
            Button {
                withAnimation { weekOffset -= 1 }
            } label: {
                Image(systemName: "chevron.left")
                    .font(.title3)
                    .foregroundStyle(Color.nextcloudBlue)
            }

            Spacer()

            VStack(spacing: 2) {
                Text(weekLabel)
                    .font(.headline)
                if weekOffset == 0 || weekOffset == 1 || weekOffset == -1 {
                    Text(weekRangeString)
                        .font(.caption)
                        .foregroundStyle(.secondary)
                }
            }

            Spacer()

            Button {
                withAnimation { weekOffset += 1 }
            } label: {
                Image(systemName: "chevron.right")
                    .font(.title3)
                    .foregroundStyle(Color.nextcloudBlue)
            }
        }
    }
}


// MARK: - Day Row

fileprivate struct MealPlanDayRow: View {
    let date: Date
    let entries: [MealPlanEntry]
    let isToday: Bool
    let onAdd: () -> Void
    let onRemove: (MealPlanEntry) -> Void

    private var dayNumber: String {
        let formatter = DateFormatter()
        formatter.dateFormat = "d"
        return formatter.string(from: date)
    }

    private var dayName: String {
        let formatter = DateFormatter()
        formatter.dateFormat = "EEE"
        return formatter.string(from: date).uppercased()
    }

    var body: some View {
        HStack(alignment: .center, spacing: 12) {
            // Day label
            VStack(spacing: 2) {
                Text(dayName)
                    .font(.caption2)
                    .fontWeight(.medium)
                    .foregroundStyle(isToday ? .white : .secondary)
                Text(dayNumber)
                    .font(.title3)
                    .fontWeight(.semibold)
                    .foregroundStyle(isToday ? .white : .primary)
            }
            .frame(width: 44, height: 54)
            .background(
                RoundedRectangle(cornerRadius: 10)
                    .fill(isToday ? Color.nextcloudBlue : Color.clear)
            )

            // Entry or add button
            if let entry = entries.first, let recipeIdInt = Int(entry.recipeId) {
                NavigationLink(value: Recipe(
                    name: entry.recipeName,
                    keywords: nil,
                    dateCreated: nil,
                    dateModified: nil,
                    imageUrl: nil,
                    imagePlaceholderUrl: nil,
                    recipe_id: recipeIdInt
                )) {
                    MealPlanEntryCard(entry: entry, onRemove: {
                        onRemove(entry)
                    })
                }
                .buttonStyle(.plain)
            } else if let entry = entries.first {
                MealPlanEntryCard(entry: entry, onRemove: {
                    onRemove(entry)
                })
            } else {
                Button(action: onAdd) {
                    Image(systemName: "plus")
                        .font(.subheadline)
                        .foregroundStyle(Color.nextcloudBlue)
                        .frame(maxWidth: .infinity, minHeight: 44)
                        .background(
                            RoundedRectangle(cornerRadius: 8)
                                .fill(Color.nextcloudBlue.opacity(0.1))
                        )
                }
            }
        }
        .padding(.horizontal)
        .padding(.vertical, 8)

        Divider()
            .padding(.leading, 68)
    }
}


// MARK: - Entry Card

fileprivate struct MealPlanEntryCard: View {
    @EnvironmentObject var appState: AppState
    let entry: MealPlanEntry
    let onRemove: () -> Void

    @State private var recipeThumb: UIImage?
    @State private var totalTimeText: String?

    var body: some View {
        HStack(spacing: 8) {
            if let recipeThumb {
                Image(uiImage: recipeThumb)
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .frame(width: 44)
                    .clipShape(RoundedRectangle(cornerRadius: 6))
            } else {
                LinearGradient(
                    gradient: Gradient(colors: [.ncGradientDark, .ncGradientLight]),
                    startPoint: .topLeading,
                    endPoint: .bottomTrailing
                )
                .frame(width: 44)
                .overlay {
                    Image(systemName: "fork.knife")
                        .font(.caption2)
                        .foregroundStyle(.white.opacity(0.7))
                }
                .clipShape(RoundedRectangle(cornerRadius: 6))
            }

            VStack(alignment: .leading, spacing: 2) {
                Text(entry.recipeName)
                    .font(.subheadline)
                    .lineLimit(3)
                    .fixedSize(horizontal: false, vertical: true)

                if let totalTimeText {
                    HStack(spacing: 3) {
                        Image(systemName: "clock")
                            .font(.caption2)
                        Text(totalTimeText)
                            .font(.caption2)
                    }
                    .foregroundStyle(.secondary)
                }
            }

            Spacer(minLength: 0)
        }
        .frame(maxWidth: .infinity, alignment: .leading)
        .padding(6)
        .background(
            RoundedRectangle(cornerRadius: 8)
                .fill(Color(.secondarySystemBackground))
        )
        .contextMenu {
            Button(role: .destructive) {
                onRemove()
            } label: {
                Label("Remove", systemImage: "trash")
            }
        }
        .task {
            guard let recipeIdInt = Int(entry.recipeId) else { return }
            recipeThumb = await appState.getImage(
                id: recipeIdInt,
                size: .THUMB,
                fetchMode: UserSettings.shared.storeThumb ? .preferLocal : .onlyServer
            )
            if let detail = await appState.getRecipe(
                id: recipeIdInt,
                fetchMode: UserSettings.shared.storeRecipes ? .preferLocal : .onlyServer
            ) {
                if let totalTime = detail.totalTime, let text = DurationComponents.ptToText(totalTime) {
                    totalTimeText = text
                } else if let prepTime = detail.prepTime, let text = DurationComponents.ptToText(prepTime) {
                    totalTimeText = text
                }
            }
        }
    }
}


// MARK: - Recipe Picker Sheet

struct RecipePickerForMealPlan: View {
    @EnvironmentObject var mealPlan: MealPlanManager
    @EnvironmentObject var appState: AppState
    @Environment(\.dismiss) private var dismiss

    let date: Date

    @State private var searchText = ""
    @State private var allRecipes: [Recipe] = []

    private var filteredRecipes: [Recipe] {
        if searchText.isEmpty {
            return allRecipes
        }
        return allRecipes.filter {
            $0.name.localizedCaseInsensitiveContains(searchText)
        }
    }

    private var dateLabel: String {
        let formatter = DateFormatter()
        formatter.dateStyle = .medium
        return formatter.string(from: date)
    }

    var body: some View {
        NavigationStack {
            List {
                ForEach(filteredRecipes, id: \.recipe_id) { recipe in
                    Button {
                        mealPlan.assignRecipe(
                            recipeId: String(recipe.recipe_id),
                            recipeName: recipe.name,
                            toDates: [date]
                        )
                        dismiss()
                    } label: {
                        RecipePickerRow(recipe: recipe)
                    }
                }
            }
            .navigationTitle(dateLabel)
            .navigationBarTitleDisplayMode(.inline)
            .searchable(text: $searchText, prompt: String(localized: "Search recipes"))
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Cancel") { dismiss() }
                }
            }
        }
        .task {
            allRecipes = await appState.getRecipes()
        }
    }
}


// MARK: - Recipe Picker Row

fileprivate struct RecipePickerRow: View {
    @EnvironmentObject var appState: AppState
    let recipe: Recipe
    @State private var recipeThumb: UIImage?

    var body: some View {
        HStack(spacing: 10) {
            if let recipeThumb {
                Image(uiImage: recipeThumb)
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .frame(width: 48, height: 48)
                    .clipShape(RoundedRectangle(cornerRadius: 8))
            } else {
                LinearGradient(
                    gradient: Gradient(colors: [.ncGradientDark, .ncGradientLight]),
                    startPoint: .topLeading,
                    endPoint: .bottomTrailing
                )
                .frame(width: 48, height: 48)
                .overlay {
                    Image(systemName: "fork.knife")
                        .font(.caption)
                        .foregroundStyle(.white.opacity(0.7))
                }
                .clipShape(RoundedRectangle(cornerRadius: 8))
            }

            Text(recipe.name)
                .font(.subheadline)
                .foregroundStyle(.primary)
                .lineLimit(2)

            Spacer()
        }
        .task {
            recipeThumb = await appState.getImage(
                id: recipe.recipe_id,
                size: .THUMB,
                fetchMode: UserSettings.shared.storeThumb ? .preferLocal : .onlyServer
            )
        }
    }
}


// MARK: - Date Identifiable Extension

extension Date: @retroactive Identifiable {
    public var id: TimeInterval { timeIntervalSince1970 }
}