import Foundation

public struct RDEPUBTextPerformanceSample: Equatable {

    public var chapterHref: String

    public var renderDuration: TimeInterval

    public var paginateDuration: TimeInterval

    public var pageCount: Int

    public var attributedStringLength: Int

    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
    }
}

public final class RDEPUBTextPerformanceSampler {

    public private(set) var samples: [RDEPUBTextPerformanceSample] = []

    public var totalBuildDuration: TimeInterval = 0

    public init() {}

    public func record(_ sample: RDEPUBTextPerformanceSample) {
        samples.append(sample)
        #if DEBUG
        print("[PERF] \(sample.chapterHref): render=\(formatMS(sample.renderDuration)) paginate=\(formatMS(sample.paginateDuration)) pages=\(sample.pageCount) cache=\(sample.cacheHit ? "HIT" : "MISS")")
        #endif
    }

    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)"
    }

    public func reset() {
        samples.removeAll()
        totalBuildDuration = 0
    }

    private func formatMS(_ duration: TimeInterval) -> String {
        String(format: "%.0fms", duration * 1000)
    }
}