import { LanguageCode } from '@vendure/common/lib/generated-types';
import { Omit } from '@vendure/common/lib/omit';
import { Injector, RequestContext, VendureEvent } from '@vendure/core';
import { Attachment } from 'nodemailer/lib/mailer';

import { EmailEventHandler } from './event-handler';

/**
 * @description
 * A VendureEvent which also includes a `ctx` property containing the current
 * {@link RequestContext}, which is used to determine the channel and language
 * to use when generating the email.
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export type EventWithContext = VendureEvent & { ctx: RequestContext };

/**
 * @description
 * A VendureEvent with a {@link RequestContext} and a `data` property which contains the
 * value resolved from the {@link EmailEventHandler}`.loadData()` callback.
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export type EventWithAsyncData<Event extends EventWithContext, R> = Event & { data: R };

/**
 * @description
 * Configuration for the EmailPlugin.
 *
 * @docsCategory EmailPlugin
 * @docsPage EmailPluginOptions
 * */
export interface EmailPluginOptions {
    /**
     * @description
     * The path to the location of the email templates. In a default Vendure installation,
     * the templates are installed to `<project root>/vendure/email/templates`.
     */
    templatePath: string;
    /**
     * @description
     * Configures how the emails are sent.
     */
    transport: EmailTransportOptions;
    /**
     * @description
     * An array of {@link EmailEventHandler}s which define which Vendure events will trigger
     * emails, and how those emails are generated.
     */
    handlers: EmailEventHandler[];
    /**
     * @description
     * An object containing variables which are made available to all templates. For example,
     * the storefront URL could be defined here and then used in the "email address verification"
     * email.
     */
    globalTemplateVars?: { [key: string]: any };
    /**
     * @description
     * An optional allowed EmailSender, used to allow custom implementations of the send functionality
     * while still utilizing the existing emailPlugin functionality.
     *
     * @default NodemailerEmailSender
     */
    emailSender?: EmailSender;
    /**
     * @description
     * An optional allowed EmailGenerator, used to allow custom email generation functionality to
     * better match with custom email sending functionality.
     *
     * @default HandlebarsMjmlGenerator
     */
    emailGenerator?: EmailGenerator;
}

/**
 * @description
 * Configuration for running the EmailPlugin in development mode.
 *
 * @docsCategory EmailPlugin
 * @docsPage EmailPluginOptions
 */
export interface EmailPluginDevModeOptions extends Omit<EmailPluginOptions, 'transport'> {
    devMode: true;
    /**
     * @description
     * The path to which html email files will be saved rather than being sent.
     */
    outputPath: string;
    /**
     * @description
     * The route to the dev mailbox server.
     */
    route: string;
}

/**
 * @description
 * The credentials used for sending email via SMTP
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export interface SMTPCredentials {
    /** @description The username */
    user: string;
    /** @description The password */
    pass: string;
}

/**
 * @description
 * A union of all the possible transport options for sending emails.
 *
 * @docsCategory EmailPlugin
 * @docsPage Transport Options
 */
export type EmailTransportOptions =
    | SMTPTransportOptions
    | SendmailTransportOptions
    | FileTransportOptions
    | NoopTransportOptions
    | TestingTransportOptions;

/**
 * @description
 * A subset of the SMTP transport options of [Nodemailer](https://nodemailer.com/smtp/)
 *
 * @docsCategory EmailPlugin
 * @docsPage Transport Options
 */
export interface SMTPTransportOptions {
    type: 'smtp';
    /**
     * @description
     * the hostname or IP address to connect to (defaults to ‘localhost’)
     */
    host: string;
    /**
     * @description
     * The port to connect to (defaults to 25 or 465)
     */
    port: number;
    /**
     * @description
     * Defines authentication data
     */
    auth: SMTPCredentials;
    /**
     * @description
     * Defines if the connection should use SSL (if true) or not (if false)
     */
    secure?: boolean;
    /**
     * @description
     * Turns off STARTTLS support if true
     */
    ignoreTLS?: boolean;
    /**
     * @description
     * Forces the client to use STARTTLS. Returns an error if upgrading the connection is not possible or fails.
     */
    requireTLS?: boolean;
    /**
     * @description
     * Optional hostname of the client, used for identifying to the server
     */
    name?: string;
    /**
     * @description
     * The local interface to bind to for network connections
     */
    localAddress?: string;
    /**
     * @description
     * Defines preferred authentication method, e.g. ‘PLAIN’
     */
    authMethod?: string;
    /**
     * @description
     * If true, uses the configured {@link VendureLogger} to log messages from Nodemailer as it interacts with
     * the SMTP server.
     *
     * @default false
     */
    logging?: boolean;
    /**
     * @description
     * If set to true, then logs SMTP traffic without message content.
     *
     * @default false
     */
    transactionLog?: boolean;
    /**
     * @description
     * If set to true, then logs SMTP traffic and message content, otherwise logs only transaction events.
     *
     * @default false
     */
    debug?: boolean;
}

/**
 * @description
 * Uses the local Sendmail program to send the email.
 *
 * @docsCategory EmailPlugin
 * @docsPage Transport Options
 */
export interface SendmailTransportOptions {
    type: 'sendmail';
    /** path to the sendmail command (defaults to ‘sendmail’) */
    path?: string;
    /** either ‘windows’ or ‘unix’ (default). Forces all newlines in the output to either use Windows syntax <CR><LF> or Unix syntax <LF> */
    newline?: string;
}

/**
 * @description
 * Outputs the email as an HTML file for development purposes.
 *
 * @docsCategory EmailPlugin
 * @docsPage Transport Options
 */
export interface FileTransportOptions {
    type: 'file';
    /** The directory in which the emails will be saved */
    outputPath: string;
    /** When set to true, a raw text file will be output rather than an HTML file */
    raw?: boolean;
}

/**
 * @description
 * Does nothing with the generated email. Intended for use in testing where we don't care about the email transport,
 * or when using a custom {@link EmailSender} which does not require transport options.
 *
 * @docsCategory EmailPlugin
 * @docsPage Transport Options
 */
export interface NoopTransportOptions {
    type: 'none';
}

/**
 * @description
 * The final, generated email details to be sent.
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export interface EmailDetails<Type extends 'serialized' | 'unserialized' = 'unserialized'> {
    from: string;
    recipient: string;
    subject: string;
    body: string;
    attachments: Array<Type extends 'serialized' ? SerializedAttachment : Attachment>;
}

/**
 * @description
 * Forwards the raw GeneratedEmailContext object to a provided callback, for use in testing.
 *
 * @docsCategory EmailPlugin
 * @docsPage Transport Options
 */
export interface TestingTransportOptions {
    type: 'testing';
    /**
     * @description
     * Callback to be invoked when an email would be sent.
     */
    onSend: (details: EmailDetails) => void;
}

/**
 * @description
 * An EmailSender is responsible for sending the email, e.g. via an SMTP connection
 * or using some other mail-sending API. By default, the EmailPlugin uses the
 * {@link NodemailerEmailSender}, but it is also possible to supply a custom implementation:
 *
 * @example
 * ```TypeScript
 * const sgMail = require('\@sendgrid/mail');
 *
 * sgMail.setApiKey(process.env.SENDGRID_API_KEY);
 *
 * class SendgridEmailSender implements EmailSender {
 *   async send(email: EmailDetails) {
 *     await sgMail.send({
 *       to: email.recipient,
 *       from: email.from,
 *       subject: email.subject,
 *       html: email.body,
 *     });
 *   }
 * }
 *
 * const config: VendureConfig = {
 *   logger: new DefaultLogger({ level: LogLevel.Debug })
 *   // ...
 *   plugins: [
 *     EmailPlugin.init({
 *        // ... template, handlers config omitted
 *       transport: { type: 'none' },
 *        emailSender: new SendgridEmailSender(),
 *     }),
 *   ],
 * };
 * ```
 *
 * @docsCategory EmailPlugin
 * @docsPage EmailSender
 * @docsWeight 0
 */
export interface EmailSender {
    send: (email: EmailDetails, options: EmailTransportOptions) => void | Promise<void>;
}

/**
 * @description
 * An EmailGenerator generates the subject and body details of an email.
 *
 * @docsCategory EmailPlugin
 * @docsPage EmailGenerator
 * @docsWeight 0
 */
export interface EmailGenerator<T extends string = any, E extends VendureEvent = any> {
    /**
     * @description
     * Any necessary setup can be performed here.
     */
    onInit?(options: EmailPluginOptions): void | Promise<void>;

    /**
     * @description
     * Given a subject and body from an email template, this method generates the final
     * interpolated email text.
     */
    generate(
        from: string,
        subject: string,
        body: string,
        templateVars: { [key: string]: any },
    ): Omit<EmailDetails, 'recipient' | 'attachments'>;
}

/**
 * @description
 * A function used to load async data for use by an {@link EmailEventHandler}.
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export type LoadDataFn<Event extends EventWithContext, R> = (context: {
    event: Event;
    injector: Injector;
}) => Promise<R>;

export type OptionalTuNullable<O> = {
    [K in keyof O]-?: undefined extends O[K] ? NonNullable<O[K]> | null : O[K];
};

/**
 * @description
 * An object defining a file attachment for an email. Based on the object described
 * [here in the Nodemailer docs](https://nodemailer.com/message/attachments/), but
 * only uses the `path` property to define a filesystem path or a URL pointing to
 * the attachment file.
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export type EmailAttachment = Omit<Attachment, 'content' | 'raw'> & { path: string };

export type SerializedAttachment = OptionalTuNullable<EmailAttachment>;

export type IntermediateEmailDetails = {
    type: string;
    from: string;
    recipient: string;
    templateVars: any;
    subject: string;
    templateFile: string;
    attachments: SerializedAttachment[];
};

/**
 * @description
 * Configures the {@link EmailEventHandler} to handle a particular channel & languageCode
 * combination.
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export interface EmailTemplateConfig {
    /**
     * @description
     * Specifies the channel to which this configuration will apply. If set to `'default'`, it will be applied to all
     * channels.
     */
    channelCode: string | 'default';
    /**
     * @description
     * Specifies the languageCode to which this configuration will apply. If set to `'default'`, it will be applied to all
     * languages.
     */
    languageCode: LanguageCode | 'default';
    /**
     * @description
     * Defines the file name of the Handlebars template file to be used to when generating this email.
     */
    templateFile: string;
    /**
     * @description
     * A string defining the email subject line. Handlebars variables defined in the `templateVars` object may
     * be used inside the subject.
     */
    subject: string;
}

/**
 * @description
 * A function used to define template variables available to email templates.
 * See {@link EmailEventHandler}.setTemplateVars().
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export type SetTemplateVarsFn<Event> = (
    event: Event,
    globals: { [key: string]: any },
) => { [key: string]: any };

/**
 * @description
 * A function used to define attachments to be sent with the email.
 * See https://nodemailer.com/message/attachments/ for more information about
 * how attachments work in Nodemailer.
 *
 * @docsCategory EmailPlugin
 * @docsPage Email Plugin Types
 */
export type SetAttachmentsFn<Event> = (event: Event) => EmailAttachment[] | Promise<EmailAttachment[]>;