import React, { ReactNode } from 'react';
import { defineMessages, FormattedMessage as Message } from 'react-intl';
import { Helmet } from 'react-helmet-async';
import { SlideMotion } from 'app/components/ui/motion';
import { ScrollIntoView } from 'app/components/ui/scroll';
import { Input, Button, Form, FormModel, FormError } from 'app/components/ui/form';
import { BackButton } from 'app/components/profile/ProfileForm';
import styles from 'app/components/profile/profileForm.scss';
import helpLinks from 'app/components/auth/helpLinks.scss';
import Stepper from 'app/components/ui/stepper';

import changeEmail from './changeEmail.scss';

const STEPS_TOTAL = 3;

export type ChangeEmailStep = 0 | 1 | 2;

interface Props {
    onChangeStep: (step: ChangeEmailStep) => void;
    email: string;
    stepForms: Array<FormModel>;
    onSubmit: (step: ChangeEmailStep, form: FormModel) => Promise<void>;
    step: ChangeEmailStep;
    code?: string;
}

interface State {
    newEmail: string | null;
    activeStep: ChangeEmailStep;
    code: string;
}

interface FormStepParams {
    form: FormModel;
    isActiveStep: boolean;
    isCodeSpecified: boolean;
    email: string;
    code?: string;
}

const labels = defineMessages({
    changeEmailButton: 'Change E‑mail',
    sendEmailButton: 'Send E‑mail',
    codePlaceholder: 'Paste the code here',
    newEmailPlaceholder: 'Enter new E‑mail',
});

export default class ChangeEmail extends React.Component<Props, State> {
    static get defaultProps(): Partial<Props> {
        return {
            stepForms: [new FormModel(), new FormModel(), new FormModel()],
            onChangeStep() {},
            step: 0,
        };
    }

    state: State = {
        newEmail: null,
        activeStep: this.props.step,
        code: this.props.code || '',
    };

    static getDerivedStateFromProps(props: Props, state: State) {
        return {
            activeStep: typeof props.step === 'number' ? props.step : state.activeStep,
            code: props.code || state.code,
        };
    }

    render() {
        const { activeStep } = this.state;
        const form = this.props.stepForms[activeStep];

        return (
            <Form form={form} onSubmit={this.onFormSubmit} onInvalid={() => this.forceUpdate()}>
                <div className={styles.contentWithBackButton} data-testid="change-email">
                    <BackButton />

                    <div className={styles.form}>
                        <div className={styles.formBody}>
                            <Message key="changeEmailTitle" defaultMessage="Change E‑mail">
                                {(pageTitle) => (
                                    <h3 className={styles.violetTitle}>
                                        <Helmet title={pageTitle as string} />
                                        {pageTitle}
                                    </h3>
                                )}
                            </Message>

                            <div className={styles.formRow}>
                                <p className={styles.description}>
                                    <Message
                                        key="changeEmailDescription"
                                        defaultMessage="To change current account E‑mail you must first verify that you own the current address and then confirm the new one."
                                    />
                                </p>
                            </div>
                        </div>
                    </div>

                    <div className={styles.stepper}>
                        <Stepper color="violet" totalSteps={STEPS_TOTAL} activeStep={activeStep} />
                    </div>

                    <div className={styles.form}>
                        {activeStep > 0 ? <ScrollIntoView /> : null}

                        {this.renderStepForms()}

                        <Button
                            color="violet"
                            type="submit"
                            block
                            label={this.isLastStep() ? labels.changeEmailButton : labels.sendEmailButton}
                        />
                    </div>

                    <div className={helpLinks.helpLinks}>
                        {this.isLastStep() ? null : (
                            <a href="#" onClick={this.onSwitchStep}>
                                <Message key="alreadyReceivedCode" defaultMessage="Already received code" />
                            </a>
                        )}
                    </div>
                </div>
            </Form>
        );
    }

    renderStepForms() {
        const { email } = this.props;
        const { activeStep, code } = this.state;
        const isCodeSpecified = !!this.props.code;

        return (
            <SlideMotion activeStep={activeStep}>
                {new Array(STEPS_TOTAL).fill(0).map((_, step) => {
                    const formParams: FormStepParams = {
                        form: this.props.stepForms[step],
                        isActiveStep: step === activeStep,
                        isCodeSpecified,
                        email,
                        code,
                    };

                    switch (step) {
                        case 0:
                            return this.renderStep0(formParams);
                        case 1:
                            return this.renderStep1(formParams);
                        case 2:
                            return this.renderStep2(formParams);
                    }
                })}
            </SlideMotion>
        );
    }

    renderStep0({ email, form }: FormStepParams): ReactNode {
        return (
            <div key="step0" data-testid="step1" className={styles.formBody}>
                <div className={styles.formRow}>
                    <p className={styles.description}>
                        <Message key="currentAccountEmail" defaultMessage="Current account E‑mail address:" />
                    </p>
                </div>

                <div className={styles.formRow}>
                    <h2 className={changeEmail.currentAccountEmail}>{email}</h2>

                    <FormError error={form.getError('email')} />
                </div>

                <div className={styles.formRow}>
                    <p className={styles.description}>
                        <Message
                            key="pressButtonToStart"
                            defaultMessage="Press the button below to send a message with the code for E‑mail change initialization."
                        />
                    </p>
                </div>
            </div>
        );
    }

    renderStep1({ email, form, code, isCodeSpecified, isActiveStep }: FormStepParams): ReactNode {
        return (
            <div key="step1" data-testid="step2" className={styles.formBody}>
                <div className={styles.formRow}>
                    <p className={styles.description}>
                        <Message
                            key="enterInitializationCode"
                            defaultMessage="The E‑mail with an initialization code for E‑mail change procedure was sent to {email}. Please enter the code into the field below:"
                            values={{
                                email: <b>{email}</b>,
                            }}
                        />
                    </p>
                </div>

                <div className={styles.formRow}>
                    <Input
                        {...form.bindField('key')}
                        required={isActiveStep}
                        disabled={isCodeSpecified}
                        value={code}
                        onChange={this.onCodeInput}
                        autoComplete="off"
                        skin="light"
                        color="violet"
                        placeholder={labels.codePlaceholder}
                    />
                </div>

                <div className={styles.formRow}>
                    <p className={styles.description}>
                        <Message
                            key="enterNewEmail"
                            defaultMessage="Then provide your new E‑mail address, that you want to use with this account. You will be mailed with confirmation code."
                        />
                    </p>
                </div>

                <div className={styles.formRow}>
                    <Input
                        {...form.bindField('email')}
                        required={isActiveStep}
                        skin="light"
                        color="violet"
                        placeholder={labels.newEmailPlaceholder}
                    />
                </div>
            </div>
        );
    }

    renderStep2({ form, code, isCodeSpecified, isActiveStep }: FormStepParams): ReactNode {
        const { newEmail } = this.state;

        return (
            <div key="step2" data-testid="step3" className={styles.formBody}>
                <div className={styles.formRow}>
                    <p className={styles.description}>
                        {newEmail ? (
                            <span>
                                <Message
                                    key="finalizationCodeWasSentToEmail"
                                    defaultMessage="The E‑mail change confirmation code was sent to {email}."
                                    values={{
                                        email: <b>{newEmail}</b>,
                                    }}
                                />{' '}
                            </span>
                        ) : null}
                        <Message
                            key="enterFinalizationCode"
                            defaultMessage="In order to confirm your new E‑mail, please enter the code received into the field below:"
                        />
                    </p>
                </div>

                <div className={styles.formRow}>
                    <Input
                        {...form.bindField('key')}
                        required={isActiveStep}
                        disabled={isCodeSpecified}
                        value={code}
                        onChange={this.onCodeInput}
                        autoComplete="off"
                        skin="light"
                        color="violet"
                        placeholder={labels.codePlaceholder}
                    />
                </div>
            </div>
        );
    }

    nextStep() {
        const { activeStep } = this.state;
        const nextStep = activeStep + 1;
        let newEmail = null;

        if (activeStep === 1) {
            newEmail = this.props.stepForms[1].value('email');
        }

        if (nextStep < STEPS_TOTAL) {
            this.setState({
                activeStep: nextStep as ChangeEmailStep,
                newEmail,
            });

            this.props.onChangeStep(nextStep as ChangeEmailStep);
        }
    }

    isLastStep() {
        return this.state.activeStep + 1 === STEPS_TOTAL;
    }

    onSwitchStep = (event: React.MouseEvent<HTMLAnchorElement>) => {
        event.preventDefault();

        this.nextStep();
    };

    onCodeInput = (event: React.ChangeEvent<HTMLInputElement>) => {
        const { value } = event.target;

        if (this.props.code) {
            return;
        }

        this.setState({
            code: value,
        });
    };

    onFormSubmit = () => {
        const { activeStep } = this.state;
        const form = this.props.stepForms[activeStep];
        const promise = this.props.onSubmit(activeStep, form);

        if (!promise || !promise.then) {
            throw new Error('Expecting promise from onSubmit');
        }

        promise.then(
            () => {
                this.nextStep();
                this.setState({
                    code: '',
                });
            },
            (resp) => {
                if (resp.errors) {
                    form.setErrors(resp.errors);
                    this.forceUpdate();
                } else {
                    return Promise.reject(resp);
                }
            },
        );
    };
}