import Foundation
import UIKit

// MARK: - 自定义 NSAttributedString 属性（对齐 WXRead 的 com.weread.highlight / com.weread.underline）

/// 高亮自定义属性名，注入到 NSAttributedString 中供 CoreText 绘制时读取
/// 对齐 WXRead 的 kWRHighlightAttributeName = "com.weread.highlight"
public let kRDEPUBHighlightAttributeName = NSAttributedString.Key("com.rdreader.highlight")

/// 下划线自定义属性名
/// 对齐 WXRead 的 kWRUnderlineAttributeName = "com.weread.underline"
public let kRDEPUBUnderlineAttributeName = NSAttributedString.Key("com.rdreader.underline")

public struct RDEPUBSelection: Codable, Equatable {
    /// 书籍标识符
    public var bookIdentifier: String?
    /// 选择发生的位置
    public var location: RDEPUBLocation
    /// 选中的文本内容
    public var text: String
    /// DOM Range 信息（JSON 序列化字符串，用于精确重建选区）
    public var rangeInfo: String?
    /// 选择创建时间
    public var createdAt: Date

    public init(
        bookIdentifier: String? = nil,
        location: RDEPUBLocation,
        text: String,
        rangeInfo: String? = nil,
        createdAt: Date = Date()
    ) {
        self.bookIdentifier = bookIdentifier
        self.location = location
        self.text = text
        self.rangeInfo = rangeInfo?.nilIfEmpty
        self.createdAt = createdAt
    }

    /// 判断是否为空选择（无文本内容）
    public var isEmpty: Bool {
        text.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
    }
}

/// 高亮样式类型
/// - highlight: 背景色高亮
/// - underline: 下划线标记
public enum RDEPUBHighlightStyle: String, Codable {
    case highlight
    case underline
}

/// 统一标注类型，对标 WXRead 的 WRBookmark 语义分层。
public enum RDEPUBAnnotationKind: String, Codable, Equatable {
    case bookmark
    case highlight
    case underline
}

/// 标注菜单操作类型，用于用户长按选中文本后的操作选项
public enum RDEPUBAnnotationMenuAction: Equatable {
    case copy
    case highlight
    case annotate
}

/// 文本偏移范围信息，用于文本 EPUB 的高亮精确定位
/// 使用字符偏移量而非 DOM Range，适用于 DTCoreText 渲染的纯文本内容
public struct RDEPUBTextOffsetRangeInfo: Codable, Equatable {
    /// 类型标识符，固定为 "text-offset"
    public var kind: String
    /// 资源路径
    public var href: String
    /// 起始字符偏移量
    public var start: Int
    /// 结束字符偏移量
    public var end: Int

    /// 初始化文本偏移范围
    /// - Parameters:
    ///   - href: 资源路径
    ///   - start: 起始字符偏移量
    ///   - end: 结束字符偏移量
    public init(href: String, start: Int, end: Int) {
        self.kind = "text-offset"
        self.href = href
        self.start = start
        self.end = end
    }

    /// 转换为 NSRange（用于 NSAttributedString 操作）
    public var nsRange: NSRange? {
        guard end > start else { return nil }
        return NSRange(location: start, length: end - start)
    }

    /// 序列化为 JSON 字符串
    public func jsonString() -> String? {
        guard let data = try? JSONEncoder().encode(self) else { return nil }
        return String(data: data, encoding: .utf8)
    }

    /// 从 JSON 字符串反序列化，校验 kind 和范围有效性
    public static func decode(from string: String?) -> RDEPUBTextOffsetRangeInfo? {
        guard let string,
              let data = string.data(using: .utf8),
              let rangeInfo = try? JSONDecoder().decode(RDEPUBTextOffsetRangeInfo.self, from: data),
              rangeInfo.kind == "text-offset",
              rangeInfo.end > rangeInfo.start else {
            return nil
        }
        return rangeInfo
    }
}

/// 文本分页截断原因，描述为什么在当前位置分页
public struct RDEPUBHighlight: Codable, Equatable {
    /// 高亮唯一标识符
    public var id: String
    /// 书籍标识符
    public var bookIdentifier: String?
    /// 高亮发生的位置
    public var location: RDEPUBLocation
    /// 高亮的文本内容
    public var text: String
    /// 范围信息（Web EPUB 为 DOM Range JSON，文本 EPUB 为字符偏移 JSON）
    public var rangeInfo: String?
    /// 高亮样式（背景色高亮或下划线）
    public var style: RDEPUBHighlightStyle
    /// 高亮颜色（CSS 颜色值，如 "#F8E16C"）
    public var color: String
    /// 用户备注
    public var note: String?
    /// 创建时间
    public var createdAt: Date

    public init(
        id: String = UUID().uuidString,
        bookIdentifier: String? = nil,
        location: RDEPUBLocation,
        text: String,
        rangeInfo: String? = nil,
        style: RDEPUBHighlightStyle = .highlight,
        color: String = "#F8E16C",
        note: String? = nil,
        createdAt: Date = Date()
    ) {
        self.id = id
        self.bookIdentifier = bookIdentifier
        self.location = location
        self.text = text
        self.rangeInfo = rangeInfo?.nilIfEmpty
        self.style = style
        self.color = color
        self.note = note?.nilIfEmpty
        self.createdAt = createdAt
    }

    /// 是否包含用户备注
    public var hasNote: Bool {
        note?.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty == false
    }

    /// 将 CSS hex 颜色转为 UIColor（对齐 WXRead 的 UIColorForHighlightColor，35% alpha）
    public var uiColor: UIColor {
        UIColor(rdHexString: color, alpha: 0.35)
            ?? UIColor(red: 248 / 255, green: 225 / 255, blue: 108 / 255, alpha: 0.35)
    }

    /// 编码键，用于 Codable 序列化/反序列化
    private enum CodingKeys: String, CodingKey {
        case id
        case bookIdentifier
        case location
        case text
        case rangeInfo
        case style
        case color
        case note
        case createdAt
    }

    /// 自定义解码器，兼容旧版本数据格式（缺失字段使用默认值）
    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(String.self, forKey: .id)
        bookIdentifier = try container.decodeIfPresent(String.self, forKey: .bookIdentifier)
        location = try container.decode(RDEPUBLocation.self, forKey: .location)
        text = try container.decode(String.self, forKey: .text)
        rangeInfo = try container.decodeIfPresent(String.self, forKey: .rangeInfo)?.nilIfEmpty
        if let rawStyle = try container.decodeIfPresent(String.self, forKey: .style),
           let decodedStyle = RDEPUBHighlightStyle(rawValue: rawStyle) {
            style = decodedStyle
        } else {
            style = .highlight
        }
        color = try container.decodeIfPresent(String.self, forKey: .color) ?? "#F8E16C"
        note = try container.decodeIfPresent(String.self, forKey: .note)?.nilIfEmpty
        createdAt = try container.decodeIfPresent(Date.self, forKey: .createdAt) ?? Date()
    }

    /// 自定义编码器
    public func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(id, forKey: .id)
        try container.encodeIfPresent(bookIdentifier, forKey: .bookIdentifier)
        try container.encode(location, forKey: .location)
        try container.encode(text, forKey: .text)
        try container.encodeIfPresent(rangeInfo, forKey: .rangeInfo)
        try container.encode(style, forKey: .style)
        try container.encode(color, forKey: .color)
        try container.encodeIfPresent(note, forKey: .note)
        try container.encode(createdAt, forKey: .createdAt)
    }

    public var annotation: RDEPUBAnnotation {
        RDEPUBAnnotation(highlight: self)
    }
}

/// 书签模型，记录用户标记的阅读位置
public struct RDEPUBBookmark: Codable, Equatable {
    /// 书签唯一标识符
    public var id: String
    /// 书籍标识符
    public var bookIdentifier: String?
    /// 书签位置
    public var location: RDEPUBLocation
    /// 章节标题（用于书签列表展示）
    public var chapterTitle: String?
    /// 用户备注
    public var note: String?
    /// 创建时间
    public var createdAt: Date

    public init(
        id: String = UUID().uuidString,
        bookIdentifier: String? = nil,
        location: RDEPUBLocation,
        chapterTitle: String? = nil,
        note: String? = nil,
        createdAt: Date = Date()
    ) {
        self.id = id
        self.bookIdentifier = bookIdentifier
        self.location = location
        self.chapterTitle = chapterTitle?.nilIfEmpty
        self.note = note?.nilIfEmpty
        self.createdAt = createdAt
    }

    /// 是否包含用户备注
    public var hasNote: Bool {
        note?.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty == false
    }

    public var annotation: RDEPUBAnnotation {
        RDEPUBAnnotation(bookmark: self)
    }
}

/// 统一标注模型，对标 WXRead 的 WRBookmark。
public struct RDEPUBAnnotation: Codable, Equatable {
    public var id: String
    public var bookIdentifier: String?
    public var kind: RDEPUBAnnotationKind
    public var location: RDEPUBLocation
    public var text: String?
    public var rangeInfo: String?
    public var color: String?
    public var chapterTitle: String?
    public var note: String?
    public var createdAt: Date

    public init(
        id: String = UUID().uuidString,
        bookIdentifier: String? = nil,
        kind: RDEPUBAnnotationKind,
        location: RDEPUBLocation,
        text: String? = nil,
        rangeInfo: String? = nil,
        color: String? = nil,
        chapterTitle: String? = nil,
        note: String? = nil,
        createdAt: Date = Date()
    ) {
        self.id = id
        self.bookIdentifier = bookIdentifier
        self.kind = kind
        self.location = location
        self.text = text?.nilIfEmpty
        self.rangeInfo = rangeInfo?.nilIfEmpty
        self.color = color?.nilIfEmpty
        self.chapterTitle = chapterTitle?.nilIfEmpty
        self.note = note?.nilIfEmpty
        self.createdAt = createdAt
    }

    public init(highlight: RDEPUBHighlight) {
        self.init(
            id: highlight.id,
            bookIdentifier: highlight.bookIdentifier,
            kind: highlight.style == .underline ? .underline : .highlight,
            location: highlight.location,
            text: highlight.text,
            rangeInfo: highlight.rangeInfo,
            color: highlight.color,
            chapterTitle: nil,
            note: highlight.note,
            createdAt: highlight.createdAt
        )
    }

    public init(bookmark: RDEPUBBookmark) {
        self.init(
            id: bookmark.id,
            bookIdentifier: bookmark.bookIdentifier,
            kind: .bookmark,
            location: bookmark.location,
            text: nil,
            rangeInfo: nil,
            color: nil,
            chapterTitle: bookmark.chapterTitle,
            note: bookmark.note,
            createdAt: bookmark.createdAt
        )
    }

    public var bookmark: RDEPUBBookmark? {
        guard kind == .bookmark else { return nil }
        return RDEPUBBookmark(
            id: id,
            bookIdentifier: bookIdentifier,
            location: location,
            chapterTitle: chapterTitle,
            note: note,
            createdAt: createdAt
        )
    }

    public var highlight: RDEPUBHighlight? {
        guard kind == .highlight || kind == .underline,
              let text else {
            return nil
        }
        return RDEPUBHighlight(
            id: id,
            bookIdentifier: bookIdentifier,
            location: location,
            text: text,
            rangeInfo: rangeInfo,
            style: kind == .underline ? .underline : .highlight,
            color: color ?? "#F8E16C",
            note: note,
            createdAt: createdAt
        )
    }
}


private extension String {
    var nilIfEmpty: String? {
        let trimmed = trimmingCharacters(in: .whitespacesAndNewlines)
        return trimmed.isEmpty ? nil : trimmed
    }
}