import Vapor
import Foundation

/// The decoder to extract caps from JSON payloads given to the `cap` route.
private let decoder = JSONDecoder()

/// The date formatter to decode dates in requests
private let dateFormatter: DateFormatter = {
    let df = DateFormatter()
    df.dateFormat = "yy-MM-dd-HH-mm-ss"
    return df
}()

extension CapServer {

    private func ensureOperability() throws {
        guard isOperational else {
            throw Abort(.noContent)
        }
    }

    func registerRoutes(with app: Application, authenticator: Authenticator) {
        app.get("version") { _ in
            try self.ensureOperability()
            return "\(self.classifierVersion)"
        }

        // Add or change a cap
        app.postCatching("cap") { request in
            try self.ensureOperability()
            try authenticator.authorize(request)
            let data = try request.getBodyData()
            let cap = try decoder.decode(Cap.self, from: data)
            try self.addOrUpdate(cap)
        }

        // Upload an image
        app.postCatching("images", ":n") { request in
            try self.ensureOperability()
            try authenticator.authorize(request)
            guard let cap = request.parameters.get("n", as: Int.self) else {
                log("Invalid parameter for cap")
                throw Abort(.badRequest)
            }
            let data = try request.getBodyData()
            try self.save(image: data, for: cap)
        }
        // Update the classifier
        app.on(.POST, "classifier", ":version", body: .collect(maxSize: "50mb")) { request -> HTTPStatus in
            guard let version = request.parameters.get("version", as: Int.self) else {
                log("Invalid parameter for version")
                throw Abort(.badRequest)
            }
            guard version > self.classifierVersion else {
                throw Abort(.alreadyReported) // 208
            }

            try self.ensureOperability()
            try authenticator.authorize(request)
            let data = try request.getBodyData()
            try self.save(classifier: data, version: version)
            return .ok
        }

        // Update the trained classes
        app.postCatching("classes", ":date") { request in
            guard let dateString = request.parameters.get("date") else {
                log("Invalid parameter for date")
                throw Abort(.badRequest)
            }
            guard let date = dateFormatter.date(from: dateString) else {
                log("Invalid date specification")
                throw Abort(.badRequest)
            }

            try self.ensureOperability()
            try authenticator.authorize(request)
            let body = try request.getStringBody()

            self.updateTrainedClasses(content: body)
            self.removeAllEntriesInImageChangeList(before: date)
        }

        // Get the list of missing thumbnails
        app.get("thumbnails", "missing") { request in
            try self.ensureOperability()
            let missingThumbnails = self.getListOfMissingThumbnails()
            return missingThumbnails.map(String.init).joined(separator: ",")
        }

        // Upload the thumbnail of a cap
        app.postCatching("thumbnails", ":cap") { request in
            guard let cap = request.parameters.get("cap", as: Int.self) else {
                log("Invalid cap parameter for thumbnail upload")
                throw Abort(.badRequest)
            }
            try self.ensureOperability()
            try authenticator.authorize(request)
            let data = try request.getBodyData()
            self.saveThumbnail(data, for: cap)
        }

        // Delete the image of a cap
        app.postCatching("delete", ":cap", ":version") { request in
            guard let cap = request.parameters.get("cap", as: Int.self) else {
                log("Invalid cap parameter for image deletion")
                throw Abort(.badRequest)
            }
            guard let version = request.parameters.get("version", as: Int.self) else {
                log("Invalid version parameter for image deletion")
                throw Abort(.badRequest)
            }

            try self.ensureOperability()
            try authenticator.authorize(request)
            guard self.deleteImage(version: version, for: cap) else {
                throw Abort(.gone)
            }
        }
    }
}

private extension Request {

    func getBodyData() throws -> Data {
        guard let buffer = body.data else {
            log("Missing body data")
            throw CapError.invalidBody
        }
        return Data(buffer: buffer)
    }

    func getStringBody() throws -> String {
        let data = try getBodyData()
        guard let content = String(data: data, encoding: .utf8) else {
            log("Invalid string body")
            throw CapError.invalidBody
        }
        return content
    }
}