//
//  SessionsView.swift
//  OpenClimb
//
//  Created by OpenClimb on 2025-01-17.
//

import Combine
import SwiftUI

struct SessionsView: View {
    @EnvironmentObject var dataManager: ClimbingDataManager
    @State private var showingAddSession = false

    var body: some View {
        NavigationView {
            VStack(spacing: 0) {
                // Active session banner
                if let activeSession = dataManager.activeSession,
                    let gym = dataManager.gym(withId: activeSession.gymId)
                {
                    VStack(spacing: 8) {
                        ActiveSessionBanner(session: activeSession, gym: gym)
                            .padding(.horizontal)
                    }
                    .padding(.top, 8)
                }

                // Sessions list
                if dataManager.sessions.isEmpty && dataManager.activeSession == nil {
                    EmptySessionsView()
                } else {
                    SessionsList()
                }
            }
            .navigationTitle("Sessions")
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    if dataManager.gyms.isEmpty {
                        EmptyView()
                    } else if dataManager.activeSession == nil {
                        Button("Start Session") {
                            if dataManager.gyms.count == 1 {
                                dataManager.startSession(gymId: dataManager.gyms.first!.id)
                            } else {
                                showingAddSession = true
                            }
                        }
                    }
                }
            }
            .sheet(isPresented: $showingAddSession) {
                AddEditSessionView()
            }
        }
    }
}

struct ActiveSessionBanner: View {
    let session: ClimbSession
    let gym: Gym
    @EnvironmentObject var dataManager: ClimbingDataManager
    @State private var currentTime = Date()

    private let timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()

    var body: some View {
        NavigationLink(destination: SessionDetailView(sessionId: session.id)) {
            HStack {
                VStack(alignment: .leading, spacing: 4) {
                    HStack {
                        Image(systemName: "play.fill")
                            .foregroundColor(.green)
                            .font(.caption)
                        Text("Active Session")
                            .font(.headline)
                            .fontWeight(.bold)
                    }

                    Text(gym.name)
                        .font(.subheadline)
                        .foregroundColor(.secondary)

                    if let startTime = session.startTime {
                        Text(formatDuration(from: startTime, to: currentTime))
                            .font(.caption)
                            .foregroundColor(.secondary)
                    }
                }

                Spacer()

                Button("End") {
                    dataManager.endSession(session.id)
                }
                .buttonStyle(.borderedProminent)
                .controlSize(.small)
            }
            .padding()
            .background(
                RoundedRectangle(cornerRadius: 12)
                    .fill(.green.opacity(0.1))
                    .stroke(.green.opacity(0.3), lineWidth: 1)
            )
        }
        .buttonStyle(.plain)
        .onReceive(timer) { _ in
            currentTime = Date()
        }
    }

    private func formatDuration(from start: Date, to end: Date) -> String {
        let interval = end.timeIntervalSince(start)
        let hours = Int(interval) / 3600
        let minutes = Int(interval) % 3600 / 60
        let seconds = Int(interval) % 60

        if hours > 0 {
            return String(format: "%dh %dm %ds", hours, minutes, seconds)
        } else if minutes > 0 {
            return String(format: "%dm %ds", minutes, seconds)
        } else {
            return String(format: "%ds", seconds)
        }
    }
}

struct SessionsList: View {
    @EnvironmentObject var dataManager: ClimbingDataManager

    private var completedSessions: [ClimbSession] {
        dataManager.sessions
            .filter { $0.status == .completed }
            .sorted { $0.date > $1.date }
    }

    var body: some View {
        List(completedSessions) { session in
            NavigationLink(destination: SessionDetailView(sessionId: session.id)) {
                SessionRow(session: session)
            }
        }
        .listStyle(.plain)
    }
}

struct SessionRow: View {
    let session: ClimbSession
    @EnvironmentObject var dataManager: ClimbingDataManager

    private var gym: Gym? {
        dataManager.gym(withId: session.gymId)
    }

    var body: some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack {
                Text(gym?.name ?? "Unknown Gym")
                    .font(.headline)
                    .fontWeight(.semibold)

                Spacer()

                Text(formatDate(session.date))
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            if let duration = session.duration {
                Text("Duration: \(duration) minutes")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            }

            if let notes = session.notes, !notes.isEmpty {
                Text(notes)
                    .font(.caption)
                    .foregroundColor(.secondary)
                    .lineLimit(2)
            }
        }
        .padding(.vertical, 4)
    }

    private func formatDate(_ date: Date) -> String {
        let formatter = DateFormatter()
        formatter.dateStyle = .medium
        return formatter.string(from: date)
    }
}

struct EmptySessionsView: View {
    @EnvironmentObject var dataManager: ClimbingDataManager
    @State private var showingAddSession = false

    var body: some View {
        VStack(spacing: 20) {
            Spacer()

            Image(systemName: "figure.climbing")
                .font(.system(size: 60))
                .foregroundColor(.secondary)

            VStack(spacing: 8) {
                Text(dataManager.gyms.isEmpty ? "No Gyms Available" : "No Sessions Yet")
                    .font(.title2)
                    .fontWeight(.bold)

                Text(
                    dataManager.gyms.isEmpty
                        ? "Add a gym first to start tracking your climbing sessions!"
                        : "Start your first climbing session!"
                )
                .font(.body)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
                .padding(.horizontal)
            }

            if !dataManager.gyms.isEmpty {
                Button("Start Session") {
                    if dataManager.gyms.count == 1 {
                        dataManager.startSession(gymId: dataManager.gyms.first!.id)
                    } else {
                        showingAddSession = true
                    }
                }
                .buttonStyle(.borderedProminent)
                .controlSize(.large)
            }

            Spacer()
        }
        .sheet(isPresented: $showingAddSession) {
            AddEditSessionView()
        }
    }
}

#Preview {
    SessionsView()
        .environmentObject(ClimbingDataManager.preview)
}