import Foundation

// MARK: - 性能采样数据模型

/// 单个章节的性能采样数据，记录渲染和分页的耗时。
public struct RDEPUBTextPerformanceSample: Equatable {
    /// 章节文件路径
    public var chapterHref: String
    /// HTML 渲染耗时（秒）
    public var renderDuration: TimeInterval
    /// CoreText 分页耗时（秒）
    public var paginateDuration: TimeInterval
    /// 分页后的页数
    public var pageCount: Int
    /// 富文本字符长度
    public var attributedStringLength: Int
    /// 是否命中分页缓存
    public var cacheHit: Bool

    public init(
        chapterHref: String,
        renderDuration: TimeInterval,
        paginateDuration: TimeInterval,
        pageCount: Int,
        attributedStringLength: Int,
        cacheHit: Bool
    ) {
        self.chapterHref = chapterHref
        self.renderDuration = renderDuration
        self.paginateDuration = paginateDuration
        self.pageCount = pageCount
        self.attributedStringLength = attributedStringLength
        self.cacheHit = cacheHit
    }
}

// MARK: - 性能采样器

/// 书籍构建过程的性能采样器，用于监控每章的渲染和分页耗时。
///
/// 由 `RDEPUBTextBookBuilder` 在构建过程中使用，每章记录一个采样点，
/// 构建完成后输出汇总报告。
public final class RDEPUBTextPerformanceSampler {
    /// 所有章节的采样数据列表
    public private(set) var samples: [RDEPUBTextPerformanceSample] = []
    /// 整本书构建的总耗时（秒）
    public var totalBuildDuration: TimeInterval = 0

    public init() {}

    /// 记录单个章节的性能采样，并输出日志
    public func record(_ sample: RDEPUBTextPerformanceSample) {
        samples.append(sample)
        print("[PERF] \(sample.chapterHref): render=\(formatMS(sample.renderDuration)) paginate=\(formatMS(sample.paginateDuration)) pages=\(sample.pageCount) cache=\(sample.cacheHit ? "HIT" : "MISS")")
    }

    /// 生成性能汇总报告，包含总渲染/分页耗时和缓存命中率
    public func summary() -> String {
        let totalRender = samples.reduce(0) { $0 + $1.renderDuration }
        let totalPaginate = samples.reduce(0) { $0 + $1.paginateDuration }
        let hitCount = samples.filter(\.cacheHit).count
        return "[PERF] chapters=\(samples.count) render=\(formatMS(totalRender)) paginate=\(formatMS(totalPaginate)) total=\(formatMS(totalBuildDuration)) cacheHits=\(hitCount)/\(samples.count)"
    }

    /// 重置所有采样数据
    public func reset() {
        samples.removeAll()
        totalBuildDuration = 0
    }

    /// 将秒转换为毫秒格式字符串
    private func formatMS(_ duration: TimeInterval) -> String {
        String(format: "%.0fms", duration * 1000)
    }
}