//
//  HistoryStore.swift
//  划词侠 plugin
//
//  Persists last 20 actions in UserDefaults under a single JSON key.
//  Cheap, durable, no external deps. Records actionLabel + input
//  preview + output preview + timestamp.
//

import Foundation

struct HistoryEntry: Codable, Identifiable, Equatable {
    var id: UUID
    var actionLabel: String   // e.g. "翻译·中文" / "总结" / "改语气·正式"
    var inputPreview: String  // truncated to 80 chars
    var outputPreview: String // truncated to 120 chars
    var timestamp: Date

    init(id: UUID = UUID(),
         actionLabel: String,
         inputPreview: String,
         outputPreview: String,
         timestamp: Date = Date()) {
        self.id = id
        self.actionLabel = actionLabel
        self.inputPreview = inputPreview
        self.outputPreview = outputPreview
        self.timestamp = timestamp
    }
}

enum HistoryStore {
    private static let key = "com.mioisland.plugin.clipper.history.v1"
    private static let maxEntries = 20

    static func load() -> [HistoryEntry] {
        guard let data = UserDefaults.standard.data(forKey: key) else { return [] }
        return (try? JSONDecoder().decode([HistoryEntry].self, from: data)) ?? []
    }

    static func save(_ entries: [HistoryEntry]) {
        guard let data = try? JSONEncoder().encode(entries) else { return }
        UserDefaults.standard.set(data, forKey: key)
    }

    static func append(_ entry: HistoryEntry) -> [HistoryEntry] {
        var list = load()
        list.insert(entry, at: 0)
        if list.count > maxEntries { list = Array(list.prefix(maxEntries)) }
        save(list)
        return list
    }

    static func truncate(_ s: String, max: Int) -> String {
        let collapsed = s.replacingOccurrences(of: "\n", with: " ")
        if collapsed.count <= max { return collapsed }
        let i = collapsed.index(collapsed.startIndex, offsetBy: max)
        return String(collapsed[..<i]) + "…"
    }
}