import { css } from '@emotion/css';
import React, { FC } from 'react';
import { useForm, Validate } from 'react-hook-form';
import { useDispatch } from 'react-redux';

import { GrafanaTheme2 } from '@grafana/data';
import { Alert, Button, Field, Input, LinkButton, TextArea, useStyles2 } from '@grafana/ui';
import { useCleanup } from 'app/core/hooks/useCleanup';
import { AlertManagerCortexConfig } from 'app/plugins/datasource/alertmanager/types';

import { useUnifiedAlertingSelector } from '../../hooks/useUnifiedAlertingSelector';
import { updateAlertManagerConfigAction } from '../../state/actions';
import { makeAMLink } from '../../utils/misc';
import { ensureDefine } from '../../utils/templates';

interface Values {
  name: string;
  content: string;
}

const defaults: Values = Object.freeze({
  name: '',
  content: '',
});

interface Props {
  existing?: Values;
  config: AlertManagerCortexConfig;
  alertManagerSourceName: string;
}

export const TemplateForm: FC<Props> = ({ existing, alertManagerSourceName, config }) => {
  const styles = useStyles2(getStyles);
  const dispatch = useDispatch();

  useCleanup((state) => state.unifiedAlerting.saveAMConfig);

  const { loading, error } = useUnifiedAlertingSelector((state) => state.saveAMConfig);

  const submit = (values: Values) => {
    // wrap content in "define" if it's not already wrapped, in case user did not do it/
    // it's not obvious that this is needed for template to work
    const content = ensureDefine(values.name, values.content);

    // add new template to template map
    const template_files = {
      ...config.template_files,
      [values.name]: content,
    };

    // delete existing one (if name changed, otherwise it was overwritten in previous step)
    if (existing && existing.name !== values.name) {
      delete template_files[existing.name];
    }

    // make sure name for the template is configured on the alertmanager config object
    const templates = [
      ...(config.alertmanager_config.templates ?? []).filter((name) => name !== existing?.name),
      values.name,
    ];

    const newConfig: AlertManagerCortexConfig = {
      template_files,
      alertmanager_config: {
        ...config.alertmanager_config,
        templates,
      },
    };
    dispatch(
      updateAlertManagerConfigAction({
        alertManagerSourceName,
        newConfig,
        oldConfig: config,
        successMessage: 'Template saved.',
        redirectPath: '/alerting/notifications',
      })
    );
  };

  const {
    handleSubmit,
    register,
    formState: { errors },
  } = useForm<Values>({
    mode: 'onSubmit',
    defaultValues: existing ?? defaults,
  });

  const validateNameIsUnique: Validate<string> = (name: string) => {
    return !config.template_files[name] || existing?.name === name
      ? true
      : 'Another template with this name already exists.';
  };

  return (
    <form onSubmit={handleSubmit(submit)}>
      <h4>{existing ? 'Edit message template' : 'Create message template'}</h4>
      {error && (
        <Alert severity="error" title="Error saving template">
          {error.message || (error as any)?.data?.message || String(error)}
        </Alert>
      )}
      <Field label="Template name" error={errors?.name?.message} invalid={!!errors.name?.message} required>
        <Input
          {...register('name', {
            required: { value: true, message: 'Required.' },
            validate: { nameIsUnique: validateNameIsUnique },
          })}
          placeholder="Give your template a name"
          width={42}
          autoFocus={true}
        />
      </Field>
      <Field
        description={
          <>
            You can use the{' '}
            <a
              href="https://pkg.go.dev/text/template?utm_source=godoc"
              target="__blank"
              rel="noreferrer"
              className={styles.externalLink}
            >
              Go templating language
            </a>
            .{' '}
            <a
              href="https://prometheus.io/blog/2016/03/03/custom-alertmanager-templates/"
              target="__blank"
              rel="noreferrer"
              className={styles.externalLink}
            >
              More info about alertmanager templates
            </a>
          </>
        }
        label="Content"
        error={errors?.content?.message}
        invalid={!!errors.content?.message}
        required
      >
        <TextArea
          {...register('content', { required: { value: true, message: 'Required.' } })}
          className={styles.textarea}
          placeholder="Message"
          rows={12}
        />
      </Field>
      <div className={styles.buttons}>
        {loading && (
          <Button disabled={true} icon="fa fa-spinner" variant="primary">
            Saving...
          </Button>
        )}
        {!loading && (
          <Button type="submit" variant="primary">
            Save template
          </Button>
        )}
        <LinkButton
          disabled={loading}
          href={makeAMLink('alerting/notifications', alertManagerSourceName)}
          variant="secondary"
          type="button"
          fill="outline"
        >
          Cancel
        </LinkButton>
      </div>
    </form>
  );
};

const getStyles = (theme: GrafanaTheme2) => ({
  externalLink: css`
    color: ${theme.colors.text.secondary};
    text-decoration: underline;
  `,
  buttons: css`
    & > * + * {
      margin-left: ${theme.spacing(1)};
    }
  `,
  textarea: css`
    max-width: 758px;
  `,
});