import Foundation

enum RDEPUBAsset: String {

    case rangyCoreScript = "rangy-core"

    case rangySerializerScript = "rangy-serializer"

    case cssInjectorScript = "cssInjector"

    case weReadAPIScript = "WeReadApi"

    case bridgeScript = "epub-bridge"

    case fixedLayoutTemplate = "epub-fixed-layout"

    case wxReadDefaultCSS = "wxread-default"

    case wxReadReplaceCSS = "wxread-replace"

    case wxReadDarkCSS = "wxread-dark"

    case wxReadLatinReplaceCSS = "wxread-replace-latin"

    var fileExtension: String {
        switch self {
        case .rangyCoreScript, .rangySerializerScript, .cssInjectorScript, .weReadAPIScript, .bridgeScript:
            return "js"
        case .fixedLayoutTemplate:
            return "html"
        case .wxReadDefaultCSS, .wxReadReplaceCSS, .wxReadDarkCSS, .wxReadLatinReplaceCSS:
            return "css"
        }
    }
}

enum RDEPUBAssetRepository {

    static func string(for asset: RDEPUBAsset, replacements: [String: String] = [:]) -> String {
        guard let url = resourceBundle.url(forResource: asset.rawValue, withExtension: asset.fileExtension),
              var content = try? String(contentsOf: url, encoding: .utf8) else {
            assertionFailure("Missing EPUB asset: \(asset.rawValue).\(asset.fileExtension)")
            return ""
        }

        for (token, value) in replacements {
            content = content.replacingOccurrences(of: "{{\(token)}}", with: value)
        }
        return content
    }

    private static var resourceBundle: Bundle {
        if let bundle = resolvedBundle {
            return bundle
        }
        return Bundle(for: RDEPUBAssetBundleToken.self)
    }

    private static var resolvedBundle: Bundle? = {
        let hostBundles = [Bundle(for: RDEPUBAssetBundleToken.self), Bundle.main] + Bundle.allFrameworks + Bundle.allBundles
        for hostBundle in hostBundles {
            for bundleName in ["RDEpubReaderViewAssets", "RDReaderViewAssets"] {
                if let url = hostBundle.url(forResource: bundleName, withExtension: "bundle"),
                   let bundle = Bundle(url: url) {
                    return bundle
                }
            }
        }
        return nil
    }()
}

private final class RDEPUBAssetBundleToken {}