import Elementary
import Foundation
import Infrastructure
import Persistence

/// The one passkey screen, which both signs in and joins. Drawn bare, without the site's navigation: its only way out is back.
///
/// A real passkey creates an account, or signs in one created with a passkey — see ``PasskeyController``. The demo accounts have none, so
/// the stubbed demo sign-in stays beside it — see ``SessionController``.
struct SignInPage {

    // MARK: Properties

    let analytics: Analytics?
    let assetVersion: String?
    let locale: Locale

    /// What went wrong with the last attempt, or `nil` when nothing did.
    let error: String?

    /// What the visitor was about to do, or `nil` when they came here directly.
    let intent: String?

    /// The path the visitor returns to, signed in or not.
    let returnPath: String

    // MARK: Initializers

    /// Creates the sign-in screen.
    /// - Parameters:
    ///   - returnPath: the path the visitor returns to, signed in or not.
    ///   - intent: what the visitor was about to do, or `nil` (the default) when they came here directly.
    ///   - error: what went wrong with the last attempt, or `nil` (the default) when nothing did.
    ///   - assetVersion: the version token appended to the page's asset URLs, or `nil` (the default) to leave them unversioned.
    ///   - analytics: the analytics tracker embedded in the document head, or `nil` (the default) to omit it.
    init(
        returnPath: String,
        intent: String? = nil,
        error: String? = nil,
        assetVersion: String? = nil,
        analytics: Analytics? = nil
    ) {
        self.analytics = analytics
        self.assetVersion = assetVersion
        self.error = error
        self.intent = intent
        self.locale = .init(identifier: "en")
        self.returnPath = returnPath
    }

}

// MARK: - Page

extension SignInPage: Page {

    // MARK: Computed

    var content: some HTML {
        div(.class("gate")) {
            header(.class("gate__bar")) {
                a(
                    .class("gate__close"),
                    .href(returnPath),
                    .custom(name: "aria-label", value: "Close and go back")
                ) {
                    Icon(.close)
                }
                span(.class("gate__wordmark")) {
                    "CCN"
                }
            }
            main(.class("gate__main")) {
                div(.class("gate__intro")) {
                    if let intent {
                        p(.class("type-eyebrow")) {
                            intent
                        }
                    }
                    h1(.class("type-h1")) {
                        "Sign in or join"
                    }
                    p(.class("gate__lead")) {
                        "No password. Your device confirms it's you."
                    }
                }
                form(
                    .class("gate__form"),
                    .action(.Route.signIn),
                    .method(.post),
                    .custom(name: "data-passkey-form", value: "")
                ) {
                    input(
                        .type(.hidden),
                        .name("return"),
                        .value(returnPath)
                    )
                    // Shown by `js/passkey.js` once the browser is known to do WebAuthn.
                    button(
                        .class("button button--primary button--xl button--block"),
                        .type(.button),
                        .hidden,
                        .custom(name: "data-passkey", value: "")
                    ) {
                        Icon(.key, size: 18)
                        "Continue with passkey"
                    }
                    p(
                        .class("field__error"),
                        .custom(name: "role", value: "alert"),
                        .custom(name: "data-passkey-status", value: "")
                    ) {}
                    PasskeyUnsupported()
                    div(.class("field")) {
                        label(
                            .class("field__label"),
                            .for("email")
                        ) {
                            "New here, or on a new device? Enter your email"
                        }
                        input(
                            .class("input input--lg"),
                            .id("email"),
                            .type(.email),
                            .name("email"),
                            .placeholder("you@example.com"),
                            .custom(name: "autocomplete", value: "username webauthn")
                        )
                        .attributes(
                            .custom(name: "aria-invalid", value: "true"),
                            .custom(name: "aria-describedby", value: "email-error"),
                            when: error != nil
                        )
                        if let error {
                            p(
                                .class("field__error"),
                                .id("email-error")
                            ) {
                                error
                            }
                        }
                        p(.class("field__hint")) {
                            "Unknown email? We create your account and passkey in the same step — nothing else to fill in."
                        }
                    }
                    div(.class("notice notice--warn gate__demo")) {
                        p {
                            "Prototype: the demo accounts have no passkey. The demo sign-in trusts the email above — or signs in the demo buyer, \(AccountRepository.demoEmail), without one. To sell, use joost@kestrelrow.example."
                        }
                        button(
                            .class("button button--outline button--block"),
                            .type(.submit)
                        ) {
                            "Demo sign-in, without a passkey"
                        }
                    }
                }
                p(.class("gate__recover")) {
                    a(.href(.Route.recover)) {
                        "Lost access to your passkeys?"
                    }
                }
            }
        }
    }

    /// Kept out of search results: the screen is a step, not a destination.
    @HTMLBuilder
    var metadata: some HTML {
        meta(
            .name("robots"),
            .content("noindex")
        )
        siteMetadata
    }

    var scripts: [any Asset] {
        [StaticFile.shared, StaticFile.passkey]
    }

    var stylesheets: [any Asset] {
        [StaticFile.shared, StaticFile.signIn]
    }

    var title: String {
        "Sign in or join — CCN"
    }

}