import Foundation

public enum VPNStoreError: Error, LocalizedError {
    case extractFailed(String)
    case noConfigsFound
    case ioError(String)

    public var errorDescription: String? {
        switch self {
        case .extractFailed(let s): "Couldn't unpack the archive: \(s)"
        case .noConfigsFound: "No .ovpn configs were found in that file."
        case .ioError(let s): "File error: \(s)"
        }
    }
}

/// Manages the on-disk store of imported OpenVPN configs at
/// `~/.config/tv-anarchy/vpn/<group>/<name>.ovpn` (sidecar certs alongside). The
/// directory scan IS the source of truth (no separate manifest) — same pattern as
/// the library index. All methods touch the filesystem; call off the main thread.
public enum VPNConfigStore {
    private static let fm = FileManager.default

    public static func rootURL() -> URL {
        fm.homeDirectoryForCurrentUser.appendingPathComponent(".config/tv-anarchy/vpn", isDirectory: true)
    }

    private static func groupURL(_ group: String) -> URL {
        rootURL().appendingPathComponent(OVPNParser.sanitizeGroup(group), isDirectory: true)
    }

    // MARK: read

    /// Every imported profile, scanned from disk, grouped dir → profiles.
    public static func list() -> [OVPNProfile] {
        guard let groups = try? fm.contentsOfDirectory(at: rootURL(),
                                                       includingPropertiesForKeys: nil) else { return [] }
        var out: [OVPNProfile] = []
        for groupDir in groups where (try? groupDir.resourceValues(forKeys: [.isDirectoryKey]))?.isDirectory == true {
            let group = groupDir.lastPathComponent
            let files = (try? fm.contentsOfDirectory(at: groupDir, includingPropertiesForKeys: nil)) ?? []
            for file in files where file.pathExtension.lowercased() == "ovpn" {
                out.append(profile(for: file, group: group))
            }
        }
        return out.sorted { ($0.group, $0.name) < ($1.group, $1.name) }
    }

    public static func groups() -> [String] {
        Array(Set(list().map(\.group))).sorted()
    }

    private static func profile(for fileURL: URL, group: String) -> OVPNProfile {
        let name = fileURL.deletingPathExtension().lastPathComponent
        let parsed = (try? String(contentsOf: fileURL, encoding: .utf8)).map(OVPNParser.parse) ?? OVPNParser.Parsed()
        return OVPNProfile(id: "\(group)/\(fileURL.lastPathComponent)", name: name, group: group,
                           fileURL: fileURL, remote: parsed.remote, proto: parsed.proto,
                           requiresAuth: parsed.requiresAuth, inlineCerts: parsed.inlineCerts)
    }

    // MARK: import

    /// Import loose `.ovpn` files (and any sidecar certs they reference) into `group`.
    @discardableResult
    public static func importFiles(_ urls: [URL], group: String = "imported") throws -> [OVPNProfile] {
        let dest = groupURL(group)
        try fm.createDirectory(at: dest, withIntermediateDirectories: true)
        var imported: [OVPNProfile] = []
        for src in urls where src.pathExtension.lowercased() == "ovpn" {
            try harvest(ovpn: src, into: dest)
            imported.append(profile(for: dest.appendingPathComponent(src.lastPathComponent), group: group))
        }
        guard !imported.isEmpty else { throw VPNStoreError.noConfigsFound }
        return imported
    }

    /// Import a provider zip bundle: unpack, find every `.ovpn` (recursively), carry
    /// each one plus its referenced sidecar certs into a group named after the zip.
    @discardableResult
    public static func importZip(_ zipURL: URL) throws -> [OVPNProfile] {
        let group = OVPNParser.sanitizeGroup(zipURL.deletingPathExtension().lastPathComponent)
        let tmp = fm.temporaryDirectory.appendingPathComponent("tva-vpn-\(UUID().uuidString)", isDirectory: true)
        try fm.createDirectory(at: tmp, withIntermediateDirectories: true)
        defer { try? fm.removeItem(at: tmp) }

        // `ditto -x -k` extracts a zip natively on macOS (no PATH/unzip dependency).
        let r = ProcessRunner.run("/usr/bin/ditto", ["-x", "-k", zipURL.path, tmp.path])
        guard r.ok else { throw VPNStoreError.extractFailed(r.stderr.isEmpty ? "ditto exit \(r.status)" : r.stderr) }

        let ovpns = ovpnFiles(under: tmp)
        guard !ovpns.isEmpty else { throw VPNStoreError.noConfigsFound }

        let dest = groupURL(group)
        try fm.createDirectory(at: dest, withIntermediateDirectories: true)
        var imported: [OVPNProfile] = []
        for src in ovpns {
            try harvest(ovpn: src, into: dest)
            imported.append(profile(for: dest.appendingPathComponent(src.lastPathComponent), group: group))
        }
        return imported
    }

    /// Copy one `.ovpn` and the sidecar files it references (resolved relative to the
    /// config's own directory) into `dest`, flattening to basenames so the config's
    /// relative `ca ca.crt` references still resolve next to it. Overwrites on repeat.
    private static func harvest(ovpn src: URL, into dest: URL) throws {
        let text = (try? String(contentsOf: src, encoding: .utf8)) ?? ""
        copy(src, into: dest)
        let srcDir = src.deletingLastPathComponent()
        for ref in OVPNParser.parse(text).sidecarRefs {
            let refURL = srcDir.appendingPathComponent(ref)
            if fm.fileExists(atPath: refURL.path) { copy(refURL, into: dest) }
        }
    }

    private static func copy(_ src: URL, into dest: URL) {
        let target = dest.appendingPathComponent(src.lastPathComponent)
        try? fm.removeItem(at: target)
        try? fm.copyItem(at: src, to: target)
    }

    /// Recursively collect `.ovpn` files under a directory.
    static func ovpnFiles(under dir: URL) -> [URL] {
        guard let en = fm.enumerator(at: dir, includingPropertiesForKeys: nil) else { return [] }
        return en.compactMap { $0 as? URL }.filter { $0.pathExtension.lowercased() == "ovpn" }
    }

    // MARK: delete

    public static func delete(_ profile: OVPNProfile) throws {
        do { try fm.removeItem(at: profile.fileURL) }
        catch { throw VPNStoreError.ioError(error.localizedDescription) }
        // Drop the group dir if it's now empty (sidecars-only leftovers included).
        let groupDir = profile.fileURL.deletingLastPathComponent()
        if VPNConfigStore.ovpnFiles(under: groupDir).isEmpty { try? fm.removeItem(at: groupDir) }
    }

    public static func deleteGroup(_ group: String) throws {
        do { try fm.removeItem(at: groupURL(group)) }
        catch { throw VPNStoreError.ioError(error.localizedDescription) }
    }
}