//
//  TaskStore.swift
//  Zyquo Agent
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//
//  CRUD + persistence for AgentTasks. Each task is saved as its own JSON
//  document under `Tasks/<uuid>.json` in the app data folder (small atomic
//  writes even when a task embeds a long step history). Provides the sidebar
//  grouping (Pinned/Today/Yesterday/Previous 7 Days/Older) and full-text
//  search across titles and message history.
//

import Combine
import Foundation

@MainActor
final class TaskStore: ObservableObject {
    @Published private(set) var tasks: [AgentTask] = []
    @Published var selectedID: AgentTask.ID?
    @Published var searchText = ""
    /// Prompt handed from the empty state to the next opened task's input
    /// bar (consumed once by the detail view).
    @Published var pendingDraft: String?

    private let persistence: PersistenceService
    private static let tasksSubdirectory = "Tasks"

    init(persistence: PersistenceService = .shared) {
        self.persistence = persistence
        try? FileManager.default.createDirectory(
            at: tasksDirectory, withIntermediateDirectories: true
        )
        loadAll()
    }

    private var tasksDirectory: URL {
        persistence.rootDirectory.appendingPathComponent(Self.tasksSubdirectory)
    }

    // MARK: - CRUD

    /// Creates a new task and selects it.
    @discardableResult
    func newTask(model: AIModel?, safetyMode: SafetyMode = .guarded, personaID: UUID? = nil) -> AgentTask {
        var task = AgentTask(
            title: "New Task",
            modelID: model?.id ?? "",
            providerID: model?.provider ?? .anthropic,
            safetyMode: safetyMode
        )
        task.personaID = personaID
        tasks.insert(task, at: 0)
        save(task)
        selectedID = task.id
        return task
    }

    /// Imports task records (Settings › Advanced). Existing IDs are skipped
    /// so re-importing an export never duplicates; imported tasks arrive with
    /// any active status normalized to idle. Returns how many were added.
    @discardableResult
    func importTasks(_ imported: [AgentTask]) -> Int {
        var added = 0
        let existing = Set(tasks.map(\.id))
        for var task in imported where !existing.contains(task.id) {
            if task.status.isActive { task.status = .idle }
            tasks.append(task)
            save(task)
            added += 1
        }
        tasks.sort { $0.updatedAt > $1.updatedAt }
        return added
    }

    func task(id: AgentTask.ID) -> AgentTask? {
        tasks.first { $0.id == id }
    }

    /// Replaces the stored task and persists it; bumps `updatedAt`.
    func update(_ task: AgentTask, touch: Bool = true) {
        var task = task
        if touch { task.updatedAt = Date() }
        guard let index = tasks.firstIndex(where: { $0.id == task.id }) else { return }
        tasks[index] = task
        save(task)
    }

    func rename(_ id: AgentTask.ID, to title: String) {
        guard var task = task(id: id) else { return }
        let trimmed = title.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !trimmed.isEmpty else { return }
        task.title = trimmed
        update(task)
    }

    func togglePin(_ id: AgentTask.ID) {
        guard var task = task(id: id) else { return }
        task.pinned.toggle()
        update(task, touch: false)
    }

    func setStatus(_ status: AgentTaskStatus, for id: AgentTask.ID) {
        guard var task = task(id: id), task.status != status else { return }
        task.status = status
        update(task, touch: false)
    }

    func appendMessage(_ message: TaskMessage, to id: AgentTask.ID) {
        guard var task = task(id: id) else { return }
        task.messages.append(message)
        update(task)
    }

    /// Deletes the task record and, when requested, its workspace folder.
    func delete(_ id: AgentTask.ID, deleteWorkspace: Bool) {
        guard let task = task(id: id) else { return }
        if deleteWorkspace, let workspace = task.workspaceURL {
            // Only ever remove directories that live under the managed
            // Workspaces/ root — never an arbitrary user path.
            let root = persistence.workspacesDirectory.standardizedFileURL.path
            let target = workspace.standardizedFileURL.path
            if target.hasPrefix(root + "/") {
                try? FileManager.default.removeItem(at: workspace)
            }
        }
        tasks.removeAll { $0.id == id }
        try? FileManager.default.removeItem(at: fileURL(for: id))
        if selectedID == id { selectedID = nil }
    }

    // MARK: - Sidebar grouping & search

    struct SidebarGroup: Identifiable {
        var id: String
        var title: String
        var tasks: [AgentTask]
    }

    /// Tasks matching the search text (title + message history), newest first.
    var filteredTasks: [AgentTask] {
        let query = searchText.trimmingCharacters(in: .whitespaces)
        let sorted = tasks.sorted { $0.updatedAt > $1.updatedAt }
        guard !query.isEmpty else { return sorted }
        return sorted.filter { task in
            if task.title.localizedCaseInsensitiveContains(query) { return true }
            return task.messages.contains { $0.text.localizedCaseInsensitiveContains(query) }
        }
    }

    /// Pinned / Today / Yesterday / Previous 7 Days / Older.
    var sidebarGroups: [SidebarGroup] {
        let calendar = Calendar.current
        let now = Date()
        var pinned: [AgentTask] = []
        var today: [AgentTask] = []
        var yesterday: [AgentTask] = []
        var previousWeek: [AgentTask] = []
        var older: [AgentTask] = []

        for task in filteredTasks {
            if task.pinned {
                pinned.append(task)
            } else if calendar.isDateInToday(task.updatedAt) {
                today.append(task)
            } else if calendar.isDateInYesterday(task.updatedAt) {
                yesterday.append(task)
            } else if let days = calendar.dateComponents([.day], from: task.updatedAt, to: now).day, days < 7 {
                previousWeek.append(task)
            } else {
                older.append(task)
            }
        }

        return [
            SidebarGroup(id: "pinned", title: "Pinned", tasks: pinned),
            SidebarGroup(id: "today", title: "Today", tasks: today),
            SidebarGroup(id: "yesterday", title: "Yesterday", tasks: yesterday),
            SidebarGroup(id: "week", title: "Previous 7 Days", tasks: previousWeek),
            SidebarGroup(id: "older", title: "Older", tasks: older),
        ].filter { !$0.tasks.isEmpty }
    }

    // MARK: - Persistence

    private func fileURL(for id: AgentTask.ID) -> URL {
        tasksDirectory.appendingPathComponent("\(id.uuidString).json")
    }

    private func save(_ task: AgentTask) {
        persistence.save(task, to: "\(Self.tasksSubdirectory)/\(task.id.uuidString).json")
    }

    private func loadAll() {
        let files = (try? FileManager.default.contentsOfDirectory(
            at: tasksDirectory, includingPropertiesForKeys: nil
        )) ?? []
        var loaded: [AgentTask] = []
        for file in files where file.pathExtension == "json" {
            if let task = persistence.load(AgentTask.self, from: "\(Self.tasksSubdirectory)/\(file.lastPathComponent)") {
                loaded.append(task)
            }
        }
        // A crash mid-run must not leave phantom "Running" pills behind.
        tasks = loaded
            .map { task in
                var task = task
                if task.status.isActive { task.status = .idle }
                return task
            }
            .sorted { $0.updatedAt > $1.updatedAt }
    }
}