import React, { memo } from 'react';
import { Pressable, StyleSheet, Text, View, type StyleProp, type ViewStyle } from 'react-native';
import Ionicons from '@react-native-vector-icons/ionicons';

import { useTheme } from '../../theme';

type InfoBannerTone = 'info' | 'warning' | 'danger' | 'success' | 'brand';

type IoniconName = React.ComponentProps<typeof Ionicons>['name'];

interface InfoBannerProps {
  /** Optional — a one-line banner reads better without one. */
  title?: string;
  message: string;
  tone?: InfoBannerTone;
  /** Overrides the tone's default icon. */
  icon?: IoniconName;
  /** Renders a text action beneath the message. */
  actionLabel?: string;
  onActionPress?: () => void;
  style?: StyleProp<ViewStyle>;
}

/**
 * An inline notice — the thing to reach for instead of a toast when the message
 * has to stay on screen while the customer fixes something.
 *
 * The tone is carried by an icon as well as a colour, because a red border
 * alone tells a colour-blind customer nothing, and tells an agent holding the
 * phone in direct sunlight even less.
 */
const DEFAULT_ICON: Record<InfoBannerTone, IoniconName> = {
  info: 'information-circle',
  warning: 'warning',
  danger: 'alert-circle',
  success: 'checkmark-circle',
  brand: 'shield-checkmark',
};

const InfoBannerComponent = ({
  title,
  message,
  tone = 'info',
  icon,
  actionLabel,
  onActionPress,
  style,
}: InfoBannerProps) => {
  const theme = useTheme();

  const palette = ((): { fg: string; bg: string; border: string } => {
    switch (tone) {
      case 'warning':
        return {
          fg: theme.colors.warning,
          bg: theme.colors.warningSurface,
          border: theme.colors.warningBorder,
        };
      case 'danger':
        return {
          fg: theme.colors.danger,
          bg: theme.colors.dangerSurface,
          border: theme.colors.dangerBorder,
        };
      case 'success':
        return {
          fg: theme.colors.success,
          bg: theme.colors.successSurface,
          border: theme.colors.successBorder,
        };
      case 'brand':
        return {
          fg: theme.colors.primary,
          bg: theme.colors.primarySurface,
          border: theme.colors.primaryBorder,
        };
      case 'info':
      default:
        return {
          fg: theme.colors.info,
          bg: theme.colors.infoSurface,
          border: theme.colors.infoBorder,
        };
    }
  })();

  return (
    <View
      // Announced when it appears, which is the point of an inline notice that
      // replaces a toast.
      accessibilityRole="alert"
      accessibilityLabel={title ? `${title}. ${message}` : message}
      style={[
        styles.banner,
        {
          backgroundColor: palette.bg,
          borderColor: palette.border,
          borderRadius: theme.radius.md,
          padding: theme.spacing.sm,
          gap: theme.spacing.sm,
        },
        style,
      ]}
    >
      <Ionicons
        name={icon ?? DEFAULT_ICON[tone]}
        size={18}
        color={palette.fg}
        style={styles.icon}
      />

      <View style={styles.body}>
        {title ? (
          <Text style={[theme.text.bodyStrong, { color: theme.colors.textPrimary }]}>{title}</Text>
        ) : null}

        {/* The message stays in secondary ink rather than the tone colour.
            Tinting a whole paragraph is what makes these banners shout — the
            icon and the tinted surface already carry the tone. */}
        <Text style={[theme.text.bodySmall, { color: theme.colors.textSecondary }]}>{message}</Text>

        {actionLabel && onActionPress ? (
          <Pressable
            accessibilityRole="button"
            accessibilityLabel={actionLabel}
            onPress={onActionPress}
            // A text link inside a banner is the easiest place to ship a 20pt
            // target by accident; the hitSlop is what brings it to 44.
            hitSlop={12}
            style={styles.action}
          >
            <Text style={[theme.text.button, { color: palette.fg }]}>{actionLabel}</Text>
            <Ionicons name="chevron-forward" size={15} color={palette.fg} />
          </Pressable>
        ) : null}
      </View>
    </View>
  );
};

const styles = StyleSheet.create({
  banner: {
    flexDirection: 'row',
    borderWidth: 1,
  },
  icon: {
    // Optically aligns the icon with the first line of text rather than with
    // the centre of a paragraph that may run to four lines.
    marginTop: 1,
  },
  body: {
    flex: 1,
    gap: 2,
  },
  action: {
    flexDirection: 'row',
    alignItems: 'center',
    gap: 2,
    marginTop: 6,
    minHeight: 24,
  },
});

export const InfoBanner = memo(InfoBannerComponent);