import Foundation

public final class RDEPUBParser {
    public internal(set) var metadata = RDEPUBMetadata()
    public internal(set) var manifest: [String: RDEPUBManifestItem] = [:]
    public internal(set) var spine: [RDEPUBSpineItem] = []
    public internal(set) var tableOfContents: [EPUBTableOfContentsItem] = []
    public internal(set) var extractionRootURL: URL?
    public internal(set) var opfURL: URL?

    public var opfDirectoryURL: URL? {
        opfURL?.deletingLastPathComponent()
    }

    public init() {}

    public func makePublication() -> RDEPUBPublication {
        RDEPUBPublication(parser: self)
    }

    public func parse(epubURL: URL) throws {
        reset()

        let extractionURL = try extractArchiveIfNeeded(epubURL: epubURL)
        extractionRootURL = extractionURL

        let containerURL = extractionURL.appendingPathComponent("META-INF/container.xml")
        guard FileManager.default.fileExists(atPath: containerURL.path) else {
            throw RDEPUBParserError.missingContainerXML
        }

        let rootFilePath = try parseContainerRootFile(at: containerURL)
        let packageURL = extractionURL.appendingPathComponent(rootFilePath)
        guard FileManager.default.fileExists(atPath: packageURL.path) else {
            throw RDEPUBParserError.invalidRootFilePath(rootFilePath)
        }

        try parseOPF(at: packageURL)
    }

    public func parseOPF(at opfURL: URL) throws {
        resetPublicationState()

        guard let parser = XMLParser(contentsOf: opfURL) else {
            throw RDEPUBParserError.invalidXML(opfURL)
        }

        let delegate = OPFPackageParserDelegate()
        parser.shouldProcessNamespaces = false
        parser.delegate = delegate

        guard parser.parse() else {
            throw parser.parserError ?? RDEPUBParserError.invalidXML(opfURL)
        }

        let packageDocument = delegate.packageDocument()
        self.opfURL = opfURL
        self.metadata = packageDocument.metadata
        self.manifest = Dictionary(uniqueKeysWithValues: packageDocument.manifest.map { ($0.id, $0) })
        self.spine = try buildSpine(from: packageDocument, opfURL: opfURL)
        self.tableOfContents = parseTOC(from: packageDocument, opfURL: opfURL)
    }

    public func parseTOC() -> [EPUBTableOfContentsItem] {
        tableOfContents
    }

    public func parseNavDocument(_ navURL: URL, baseURL: URL? = nil) -> [EPUBTableOfContentsItem] {
        parseNavDocumentItems(at: navURL, baseURL: baseURL ?? navURL.deletingLastPathComponent())
    }
}