//
// SplitDetailView.swift
// Workouts
//
// Created by rzen on 7/25/25 at 3:27 PM.
//
// Copyright 2025 Rouslan Zenetl. All Rights Reserved.
//

import IndieSync
import SwiftUI
import SwiftData

struct SplitDetailView: View {
    @Environment(SyncEngine.self) private var sync
    @Environment(AppServices.self) private var services
    @Environment(\.dismiss) private var dismiss

    // Resolve the split by id, not a captured entity: a clone-on-edit swaps a seed's
    // identity mid-screen (the seed entity is deleted and a clone inserted), which
    // would dangle a stored `Split`. `currentSplitID` follows that swap.
    @State private var splitID: String
    @Query private var splits: [Split]

    @State private var showingExerciseAddSheet: Bool = false
    @State private var showingSplitEditSheet: Bool = false
    @State private var itemToEdit: Exercise? = nil
    @State private var itemToDelete: Exercise? = nil
    @AppStorage("weightUnit") private var weightUnit: WeightUnit = .lb

    init(split: Split) {
        _splitID = State(initialValue: split.id)
    }

    private var split: Split? {
        let id = sync.currentSplitID(for: splitID)
        return splits.first { $0.id == id }
    }

    var body: some View {
        Group {
            if let split {
                content(for: split)
            } else {
                // The id we held no longer maps to a live split (deleted on another
                // device, or a transient mid-clone frame). Show nothing and leave.
                ContentUnavailableView("Split Unavailable", systemImage: "dumbbell")
                    .task { dismiss() }
            }
        }
        // Editing this split (or any of its exercises, all reached from here) parks any
        // active watch run sourced from it — matched by splitID — so the watch can't keep
        // performing an exercise whose plan we're reconfiguring.
        .onAppear { services.watchBridge.setEditingSplit(sync.currentSplitID(for: splitID)) }
        .onDisappear { services.watchBridge.setEditingSplit(nil) }
    }

    @ViewBuilder
    private func content(for split: Split) -> some View {
        Form {
            Section(header: Text("What is a Split?")) {
                Text("A \"split\" is simply how you divide (or \"split up\") your weekly training across different days. Instead of working every muscle group every session, you assign certain muscle groups, movement patterns, or training emphases to specific days.")
                    .font(.caption)
            }

            // Headerless — what the exercise list is needs no label; the section
            // itself keeps the visual separation.
            if split.exercisesArray.isEmpty {
                Section {
                    Text("No exercises added yet.")
                    Button(action: { showingExerciseAddSheet.toggle() }) {
                        ListItem(title: "Add Exercise")
                    }
                }
            } else {
                Section {
                    ForEach(split.exercisesArray) { item in
                        ListItem(
                            title: item.name,
                            subtitle: item.planSummary(weightUnit: weightUnit)
                        )
                        .swipeActions {
                            Button {
                                itemToDelete = item
                            } label: {
                                Label("Delete", systemImage: "trash")
                            }
                            .tint(.red)
                            Button {
                                itemToEdit = item
                            } label: {
                                Label("Edit", systemImage: "pencil")
                            }
                            .tint(.indigo)
                        }
                    }
                    .onMove { source, destination in
                        moveExercises(from: source, to: destination)
                    }

                    Button {
                        showingExerciseAddSheet = true
                    } label: {
                        ListItem(systemName: "plus.circle", title: "Add Exercise")
                    }
                }
            }
        }
        .navigationTitle(split.name)
        .toolbar {
            ToolbarItem(placement: .primaryAction) {
                Button {
                    showingSplitEditSheet = true
                } label: {
                    Image(systemName: "pencil")
                }
            }
        }
        .sheet(isPresented: $showingExerciseAddSheet) {
            ExercisePickerView(onExerciseSelected: { exerciseNames in
                addExercises(names: exerciseNames)
            }, allowMultiSelect: true)
        }
        .sheet(isPresented: $showingSplitEditSheet) {
            SplitAddEditView(split: split) {
                dismiss()
            }
        }
        .sheet(item: $itemToEdit) { item in
            ExerciseAddEditView(exercise: item, split: split)
        }
        .confirmationDialog(
            "Delete Exercise?",
            isPresented: Binding(
                get: { itemToDelete != nil },
                set: { if !$0 { itemToDelete = nil } }
            ),
            titleVisibility: .visible,
            presenting: itemToDelete
        ) { item in
            Button("Delete", role: .destructive) {
                deleteExercise(item)
                itemToDelete = nil
            }
            Button("Cancel", role: .cancel) {
                itemToDelete = nil
            }
        } message: { item in
            Text("Remove \"\(item.name)\" from this split?")
        }
    }

    /// Reorder and renumber. Resolves the current split at call time so it
    /// follows a clone-on-edit.
    private func moveExercises(from source: IndexSet, to destination: Int) {
        guard let split else { return }
        var ordered = split.exercisesArray
        ordered.move(fromOffsets: source, toOffset: destination)

        var doc = SplitDocument(from: split)
        doc.exercises = ordered.enumerated().map { i, ex in
            var ed = ExerciseDocument(from: ex)
            ed.order = i
            return ed
        }
        doc.updatedAt = Date()
        Task { await sync.save(split: doc) }
    }

    private func addExercises(names: [String]) {
        guard let split else { return }
        var doc = SplitDocument(from: split)
        let existingNames = Set(doc.exercises.map { $0.name })
        let base = doc.exercises.count
        let newDocs = names
            .filter { !existingNames.contains($0) }
            .enumerated()
            .map { i, exName -> ExerciseDocument in
                // Seed from the library's authored `**Defaults:**` when available,
                // falling back to a plain 3×10 weighted guess; weight always starts
                // at 0 (there's no prior lift to seed it from).
                let defaults = ExerciseInfoLibrary.info(for: exName)?.defaults
                return ExerciseDocument(
                    id: ULID.make(), name: exName, order: base + i,
                    sets: defaults?.sets ?? 3, reps: defaults?.reps ?? 10, weight: 0,
                    loadType: (defaults?.loadType ?? .weight).rawValue,
                    durationSeconds: defaults?.durationSeconds ?? 0
                )
            }
        doc.exercises.append(contentsOf: newDocs)
        doc.updatedAt = Date()
        Task { await sync.save(split: doc) }

        // If a single exercise was added, open the edit sheet once the cache refreshes.
        // We rely on the observer to populate it — no direct entity reference needed.
    }

    private func deleteExercise(_ exercise: Exercise) {
        guard let split else { return }
        var doc = SplitDocument(from: split)
        doc.exercises.removeAll { $0.id == exercise.id }
        // Re-number orders after removal
        for i in doc.exercises.indices {
            doc.exercises[i].order = i
        }
        doc.updatedAt = Date()
        Task { await sync.save(split: doc) }
    }
}
