import * as React from 'react';
import { Document, Page, View, Text, Image, StyleSheet, Font, Link } from '@react-pdf/renderer';

// Register fonts (using system fonts for now, can be customized)
Font.register({
  family: 'Helvetica',
  fonts: [
    { src: '/fonts/Helvetica.ttf', fontWeight: 400 },
    { src: '/fonts/Helvetica-Bold.ttf', fontWeight: 700 },
  ],
});

// ─── Brand Tokens ────────────────────────────────────────

const C = {
  navy: '#001a4d',
  navyDeep: '#000d26',
  green: '#4da612',
  white: '#FFFFFF',
  offWhite: '#f8f9fa',
  gray200: '#e5e7eb',
  gray400: '#9ca3af',
  gray600: '#4b5563',
  gray900: '#111827',
};

const MARGIN = 56;
const HEADER_H = 52;
const FOOTER_H = 48;
const BODY_TOP = HEADER_H + 20;

const styles = StyleSheet.create({
  page: {
    color: C.gray900,
    lineHeight: 1.5,
    backgroundColor: C.white,
    paddingTop: BODY_TOP,
    paddingBottom: FOOTER_H + 40,
    paddingHorizontal: MARGIN,
    fontFamily: 'Helvetica',
  },
  header: {
    position: 'absolute',
    top: 0,
    left: 0,
    right: 0,
    height: HEADER_H,
    flexDirection: 'row',
    justifyContent: 'space-between',
    alignItems: 'flex-end',
    paddingHorizontal: MARGIN,
    paddingBottom: 12,
    borderBottomWidth: 0,
  },
  logoText: {
    fontSize: 16,
    fontWeight: 700,
    color: C.navy,
  },
  docTitleLabel: {
    fontSize: 7,
    fontWeight: 700,
    color: C.gray400,
    letterSpacing: 1.2,
    textTransform: 'uppercase',
  },
  footer: {
    position: 'absolute',
    bottom: 20,
    left: MARGIN,
    right: MARGIN,
    flexDirection: 'row',
    justifyContent: 'space-between',
    alignItems: 'center',
    borderTopWidth: 0.5,
    borderTopColor: C.gray200,
    paddingTop: 8,
  },
  footerText: {
    fontSize: 7,
    color: C.gray400,
    letterSpacing: 0.8,
    textTransform: 'uppercase',
  },
  pageTitle: {
    fontSize: 24,
    fontWeight: 700,
    color: C.navyDeep,
    marginBottom: 16,
    textTransform: 'uppercase',
    letterSpacing: -0.5,
  },
  accentBar: {
    width: 40,
    height: 3,
    backgroundColor: C.green,
    marginBottom: 24,
  },

  // Lexical Elements
  paragraph: {
    fontSize: 10,
    color: C.gray600,
    lineHeight: 1.6,
    marginBottom: 12,
  },
  heading1: {
    fontSize: 18,
    fontWeight: 700,
    color: C.navyDeep,
    marginTop: 16,
    marginBottom: 8,
  },
  heading2: {
    fontSize: 14,
    fontWeight: 700,
    color: C.navyDeep,
    marginTop: 14,
    marginBottom: 6,
  },
  heading3: {
    fontSize: 12,
    fontWeight: 700,
    color: C.navyDeep,
    marginTop: 12,
    marginBottom: 4,
  },
  list: {
    marginBottom: 12,
    marginLeft: 8,
  },
  listItem: {
    flexDirection: 'row',
    marginBottom: 4,
  },
  listItemBullet: {
    width: 12,
    fontSize: 10,
    color: C.green,
  },
  listItemContent: {
    flex: 1,
    fontSize: 10,
    color: C.gray600,
    lineHeight: 1.6,
  },
  link: {
    color: C.green,
    textDecoration: 'none',
  },
  textBold: {
    fontWeight: 700,
    fontFamily: 'Helvetica-Bold',
    color: C.navyDeep,
  },
  textItalic: {
    fontStyle: 'italic', // Not actually working without proper font set, but we will fallback
  },
});

// ─── Lexical to React-PDF Renderer ────────────────────────────────

const renderLexicalNode = (node: any, idx: number): React.ReactNode => {
  if (!node) return null;

  switch (node.type) {
    case 'text': {
      const format = node.format || 0;
      const isBold = (format & 1) !== 0;
      const isItalic = (format & 2) !== 0;

      let elementStyle: any = {};
      if (isBold) elementStyle = { ...elementStyle, ...styles.textBold };
      if (isItalic) elementStyle = { ...elementStyle, ...styles.textItalic };

      return (
        <Text key={idx} style={elementStyle}>
          {node.text}
        </Text>
      );
    }

    case 'paragraph': {
      return (
        <Text key={idx} style={styles.paragraph}>
          {node.children?.map((child: any, i: number) => renderLexicalNode(child, i))}
        </Text>
      );
    }

    case 'heading': {
      let hStyle = styles.heading3;
      if (node.tag === 'h1') hStyle = styles.heading1;
      if (node.tag === 'h2') hStyle = styles.heading2;

      return (
        <Text key={idx} style={hStyle}>
          {node.children?.map((child: any, i: number) => renderLexicalNode(child, i))}
        </Text>
      );
    }

    case 'list': {
      return (
        <View key={idx} style={styles.list}>
          {node.children?.map((child: any, i: number) => {
            if (child.type === 'listitem') {
              return (
                <View key={i} style={styles.listItem}>
                  <Text style={styles.listItemBullet}>
                    {node.listType === 'number' ? `${i + 1}.` : '•'}
                  </Text>
                  <Text style={styles.listItemContent}>
                    {child.children?.map((c: any, ci: number) => renderLexicalNode(c, ci))}
                  </Text>
                </View>
              );
            }
            return renderLexicalNode(child, i);
          })}
        </View>
      );
    }

    case 'link': {
      const href = node.fields?.url || node.url || '#';
      return (
        <Link key={idx} src={href} style={styles.link}>
          {node.children?.map((child: any, i: number) => renderLexicalNode(child, i))}
        </Link>
      );
    }

    case 'linebreak': {
      // React-PDF doesn't handle `<br/>`, but a newline char usually works inside `<Text>`.
      return <Text key={idx}>{'\n'}</Text>;
    }

    // Ignore payload blocks recursively to avoid crashing, as pages should mainly use rich text
    case 'block':
      return null;

    default:
      if (node.children) {
        return (
          <Text key={idx}>
            {node.children.map((child: any, i: number) => renderLexicalNode(child, i))}
          </Text>
        );
      }
      return null;
  }
};

interface PDFPageProps {
  page: any;
  locale?: string;
}

export const PDFPage: React.FC<PDFPageProps> = ({ page, locale = 'de' }) => {
  const dateStr = new Date().toLocaleDateString(locale === 'en' ? 'en-US' : 'de-DE', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
  });

  return (
    <Document>
      <Page size="A4" style={styles.page}>
        <View style={styles.header} fixed>
          <Text style={styles.logoText}>KLZ</Text>
          <Text style={styles.docTitleLabel}>{locale === 'en' ? 'Document' : 'Dokument'}</Text>
        </View>

        <Text style={styles.pageTitle}>{page.title}</Text>
        <View style={styles.accentBar} />

        <View>
          {page.content?.root?.children?.map((node: any, i: number) => renderLexicalNode(node, i))}
        </View>

        <View style={styles.footer} fixed>
          <Text style={styles.footerText}>KLZ CABLES</Text>
          <Text style={styles.footerText}>{dateStr}</Text>
        </View>
      </Page>
    </Document>
  );
};
