import React, {useState} from 'react';
import {Linking, Pressable, ScrollView, StyleSheet, Text, View} from 'react-native';
import {useSafeAreaInsets} from 'react-native-safe-area-context';

import {colors, radii, spacing} from '../../../theme';
import {PrimaryButton} from '../components/PrimaryButton';
import type {
  MeasurementState,
  PPGProcessingResult,
  SignalQualityIssue,
} from '../measurement/measurementTypes';

interface PPGFailureScreenProps {
  state: MeasurementState;
  message: string;
  result?: PPGProcessingResult | null;
  showOpenSettings?: boolean;
  onRetry: () => void;
  onBack: () => void;
}

const ISSUE_LABELS: Record<SignalQualityIssue, string> = {
  contactInsufficient: 'contact caméra insuffisant',
  contactInterrupted: 'contact interrompu',
  durationInsufficient: 'durée utile insuffisante',
  droppedFrames: 'images perdues',
  timestampJitter: 'cadence caméra irrégulière',
  longGap: 'interruption trop longue',
  saturation: 'image trop lumineuse / saturée',
  motionArtifacts: 'mouvements détectés',
  lowPulsatileAmplitude: 'pulsations trop faibles',
  lowSignalToNoiseRatio: 'signal trop bruité',
  tooFewPeaks: 'trop peu de battements détectés',
  tooManyRejectedPeaks: 'trop de battements rejetés',
  tooManyRejectedIntervals: 'intervalles trop irréguliers',
  methodDisagreement: 'estimations du rythme incohérentes',
  channelInstability: 'couleur du signal instable',
  nonFiniteProcessingResult: 'calcul du signal impossible',
};

const percent = (value: number): string => `${Math.round(value * 100)} %`;

function qualityLabel(result: PPGProcessingResult): string {
  switch (result.quality.level) {
    case 'good':
      return 'bonne';
    case 'medium':
      return 'moyenne';
    case 'poor':
      return 'faible';
    default:
      return 'invalide';
  }
}

export function PPGFailureScreen({
  state,
  message,
  result = null,
  showOpenSettings = false,
  onRetry,
  onBack,
}: PPGFailureScreenProps): React.JSX.Element {
  const thermal = state === 'thermalStop';
  const insets = useSafeAreaInsets();
  const [showDiagnostic, setShowDiagnostic] = useState(false);
  return (
    <ScrollView
      style={styles.scroll}
      contentContainerStyle={[
        styles.container,
        {paddingTop: insets.top + spacing.lg},
      ]}
      showsVerticalScrollIndicator={false}>
      <View style={styles.icon}>
        <Text style={styles.iconText}>{thermal ? '°' : '!'}</Text>
      </View>
      <Text style={styles.title}>
        {thermal ? 'L’iPhone doit refroidir' : 'Mesure non exploitable'}
      </Text>
      <Text style={styles.message}>{message}</Text>
      {!thermal && result !== null ? (
        <Pressable
          accessibilityRole="button"
          accessibilityState={{expanded: showDiagnostic}}
          onPress={() => setShowDiagnostic(value => !value)}
          style={styles.diagnosticToggle}>
          <Text style={styles.tipTitle}>Détails techniques</Text>
          <Text style={styles.diagnosticChevron}>{showDiagnostic ? '−' : '+'}</Text>
        </Pressable>
      ) : null}
      {!thermal && result !== null && showDiagnostic ? (
        <View style={styles.diagnosticCard}>
          <Text style={styles.tipTitle}>Diagnostic de cette mesure</Text>
          <Text style={styles.diagnosticLine}>
            Qualité : {percent(result.quality.score)} ({qualityLabel(result)})
          </Text>
          <Text style={styles.diagnosticLine}>
            Signal utile : {result.quality.usableDurationSeconds.toFixed(1)} s ·
            mouvement : {percent(result.quality.motionArtifactRatio)}
          </Text>
          <Text style={styles.diagnosticLine}>
            Saturation : {percent(result.quality.saturationRatio)} · pertes :{' '}
            {percent(result.quality.droppedFrameRatio)}
          </Text>
          <Text style={styles.diagnosticLine}>
            SNR :{' '}
            {result.quality.signalToNoiseRatio === null
              ? 'indisponible'
              : result.quality.signalToNoiseRatio.toFixed(1)}{' '}
            · battements : {result.bpm.validPeakCount}
          </Text>
          <Text style={styles.diagnosticLine}>
            Trames : {result.rawSampleCount} · rééchantillonnées :{' '}
            {result.resampledSampleCount}
          </Text>
          {result.quality.issues.length > 0 ? (
            <Text style={styles.issueText}>
              Cause(s) :{' '}
              {result.quality.issues.map(issue => ISSUE_LABELS[issue]).join(', ')}
            </Text>
          ) : null}
        </View>
      ) : null}
      <View style={styles.tipCard}>
        <Text style={styles.tipTitle}>Pour le prochain essai</Text>
        <Text style={styles.tipText}>
          Posez le doigt doucement, couvrez entièrement la caméra choisie et
          gardez la main immobile. Avec la caméra arrière, couvrez aussi le flash.
        </Text>
      </View>
      <PrimaryButton
        label={thermal ? 'Réessayer plus tard' : 'Recommencer'}
        onPress={onRetry}
      />
      {showOpenSettings ? (
        <PrimaryButton
          label="Ouvrir les réglages de l’iPhone"
          variant="secondary"
          onPress={() => Linking.openSettings().catch(() => undefined)}
        />
      ) : null}
      <PrimaryButton label="Retour" variant="ghost" onPress={onBack} />
    </ScrollView>
  );
}

const styles = StyleSheet.create({
  scroll: {
    flex: 1,
    backgroundColor: colors.background,
  },
  container: {
    flexGrow: 1,
    padding: spacing.lg,
    justifyContent: 'center',
    backgroundColor: colors.background,
  },
  icon: {
    width: 60,
    height: 60,
    borderRadius: 30,
    alignItems: 'center',
    justifyContent: 'center',
    borderWidth: 1,
    borderColor: colors.poor,
    backgroundColor: colors.accentSoft,
  },
  iconText: {
    color: colors.poor,
    fontSize: 27,
    fontWeight: '900',
  },
  title: {
    color: colors.text,
    fontSize: 32,
    lineHeight: 37,
    fontWeight: '800',
    marginTop: spacing.lg,
  },
  message: {
    color: colors.muted,
    fontSize: 15,
    lineHeight: 22,
    marginTop: spacing.sm,
  },
  diagnosticCard: {
    padding: spacing.md,
    borderRadius: radii.md,
    backgroundColor: colors.surface,
    borderWidth: 1,
    borderColor: colors.accent,
    marginTop: spacing.sm,
  },
  diagnosticToggle: {
    minHeight: 54,
    marginTop: spacing.lg,
    paddingHorizontal: spacing.md,
    borderRadius: radii.md,
    backgroundColor: colors.surface,
    borderWidth: 1,
    borderColor: colors.border,
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'space-between',
  },
  diagnosticChevron: {
    color: colors.accent,
    fontSize: 25,
    fontWeight: '300',
  },
  diagnosticLine: {
    color: colors.text,
    fontSize: 14,
    lineHeight: 21,
    marginTop: spacing.xs,
  },
  issueText: {
    color: colors.poor,
    fontSize: 14,
    lineHeight: 20,
    fontWeight: '700',
    marginTop: spacing.sm,
  },
  tipCard: {
    padding: spacing.md,
    borderRadius: radii.md,
    backgroundColor: colors.surface,
    borderWidth: 1,
    borderColor: colors.border,
    marginVertical: spacing.lg,
  },
  tipTitle: {
    color: colors.text,
    fontWeight: '700',
  },
  tipText: {
    color: colors.muted,
    lineHeight: 20,
    marginTop: spacing.xs,
  },
});