// RDEPUBWebView+Search.swift
// RDEPUBWebView 的搜索高亮扩展
// 从当前渲染请求中提取搜索展示信息，生成搜索高亮脚本并注入到 WebView 中执行。

import UIKit
import WebKit

extension RDEPUBWebView {
    private var normalSearchOverlayColor: UIColor {
        UIColor(red: 0.21, green: 0.48, blue: 0.95, alpha: 0.16)
    }

    private var activeSearchOverlayColor: UIColor {
        UIColor(red: 0.14, green: 0.42, blue: 0.95, alpha: 0.34)
    }

    /// 如果当前渲染请求包含搜索信息，注入搜索高亮脚本到 WebView
    func applySearchDecorationsIfNeeded(completion: (() -> Void)? = nil) {
        guard let webView else {
            completion?()
            return
        }

        let presentation: RDEPUBSearchPresentation?
        switch currentRenderRequest {
        case .reflowable(let request):
            presentation = request.searchPresentation
        case .fixed(let request):
            presentation = request.searchPresentation
        case .none:
            presentation = nil
        }

        let script = RDEPUBJavaScriptBridge.applySearchScript(for: presentation)
        webView.evaluateJavaScript(script) { [weak self] _, error in
            guard let self else {
                completion?()
                return
            }
            if let error {
                self.delegate?.epubWebView(self, didLogJavaScriptError: error.localizedDescription)
            }
            self.refreshNativeDecorationsIfNeeded(completion: completion)
        }
    }

    func refreshNativeDecorationsIfNeeded(completion: (() -> Void)? = nil) {
        guard let webView else {
            onDecorationsResolved?([])
            completion?()
            return
        }

        webView.evaluateJavaScript(RDEPUBJavaScriptBridge.resolveDecorationsScript()) { [weak self] result, error in
            guard let self else {
                completion?()
                return
            }
            if let error {
                self.delegate?.epubWebView(self, didLogJavaScriptError: error.localizedDescription)
                self.onDecorationsResolved?([])
                completion?()
                return
            }

            let decorations = self.nativeDecorations(from: result)
            self.onDecorationsResolved?(decorations)
            completion?()
        }
    }

    private func nativeDecorations(from result: Any?) -> [RDEPUBTextOverlayDecoration] {
        guard let payload = result as? [String: Any] else { return [] }

        let highlightDecorations = decorationList(
            from: payload["highlights"] as? [[String: Any]],
            defaultColor: overlayColor(hex: "#F8E16C", alpha: 0.45) ?? UIColor(red: 248 / 255, green: 225 / 255, blue: 108 / 255, alpha: 0.45)
        )
        let searchDecorations = decorationList(
            from: payload["search"] as? [[String: Any]],
            defaultColor: normalSearchOverlayColor
        )
        return highlightDecorations + searchDecorations
    }

    private func decorationList(
        from items: [[String: Any]]?,
        defaultColor: UIColor
    ) -> [RDEPUBTextOverlayDecoration] {
        guard let items else { return [] }

        return items.enumerated().compactMap { index, item -> RDEPUBTextOverlayDecoration? in
            guard let kindString = item["kind"] as? String,
                  let kind = RDEPUBTextOverlayDecoration.Kind(rawValue: kindString),
                  let rectPayloads = item["rects"] as? [[String: Any]] else {
                return nil
            }

            let rects = rectPayloads.compactMap { rectPayload -> CGRect? in
                guard let x = (rectPayload["x"] as? NSNumber)?.doubleValue,
                      let y = (rectPayload["y"] as? NSNumber)?.doubleValue,
                      let width = (rectPayload["width"] as? NSNumber)?.doubleValue,
                      let height = (rectPayload["height"] as? NSNumber)?.doubleValue else {
                    return nil
                }
                return CGRect(x: x, y: y, width: width, height: height)
            }
            guard !rects.isEmpty else { return nil }

            let color: UIColor
            switch kind {
            case .underline:
                let hex = item["color"] as? String ?? "#F8E16C"
                color = overlayColor(hex: hex, alpha: 1) ?? defaultColor
            case .activeSearch:
                color = activeSearchOverlayColor
            case .search:
                color = normalSearchOverlayColor
            case .highlight:
                let hex = item["color"] as? String ?? "#F8E16C"
                color = overlayColor(hex: hex, alpha: 0.45) ?? defaultColor
            case .selection, .locate:
                color = defaultColor
            }

            return RDEPUBTextOverlayDecoration(
                kind: kind,
                absoluteRange: NSRange(location: index, length: 1),
                rects: rects,
                color: color
            )
        }
    }

    private func overlayColor(hex: String, alpha: CGFloat) -> UIColor? {
        var value = hex.trimmingCharacters(in: .whitespacesAndNewlines)
        value = value.replacingOccurrences(of: "#", with: "")
        guard value.count == 6, let hexValue = Int(value, radix: 16) else { return nil }
        return UIColor(
            red: CGFloat((hexValue >> 16) & 0xFF) / 255,
            green: CGFloat((hexValue >> 8) & 0xFF) / 255,
            blue: CGFloat(hexValue & 0xFF) / 255,
            alpha: alpha
        )
    }
}