import React from 'react';
import Box from '@mui/material/Box';
import Tooltip from '@mui/material/Tooltip';
import InfoOutlinedIcon from '@mui/icons-material/InfoOutlined';
import CheckCircleOutlineIcon from '@mui/icons-material/CheckCircleOutline';
import StarRoundedIcon from '@mui/icons-material/StarRounded';
import VerifiedOutlinedIcon from '@mui/icons-material/VerifiedOutlined';
import type { SxProps, Theme } from '@mui/material/styles';
import { Typography } from '../../atoms/Typography';
import { Button } from '../../atoms/Button';
import { Badge } from '../../atoms/Badge';
import { Card } from '../../atoms/Card';
import { Link } from '../../atoms/Link';
import { Divider } from '../../atoms/Divider';

// ─── Types ───────────────────────────────────────────────────────────────────

/** Cell value types for the comparison table */
export type ComparisonCellValue =
  | { type: 'price'; amount: number }
  | { type: 'allowance'; amount: number }
  | { type: 'complimentary' }
  | { type: 'included' }
  | { type: 'poa' }
  | { type: 'unknown' }
  | { type: 'unavailable' };

export interface ComparisonLineItem {
  name: string;
  info?: string;
  value: ComparisonCellValue;
}

export interface ComparisonSection {
  heading: string;
  items: ComparisonLineItem[];
}

export interface ComparisonProvider {
  name: string;
  location: string;
  logoUrl?: string;
  rating?: number;
  reviewCount?: number;
  verified: boolean;
}

export interface ComparisonPackage {
  id: string;
  name: string;
  price: number;
  provider: ComparisonProvider;
  sections: ComparisonSection[];
  isRecommended?: boolean;
  itemizedAvailable?: boolean;
}

export interface ComparisonTableProps {
  packages: ComparisonPackage[];
  onArrange: (packageId: string) => void;
  onRemove: (packageId: string) => void;
  sx?: SxProps<Theme>;
}

// ─── Helpers ────────────────────────────────────────────────────────────────

function formatPrice(amount: number): string {
  return `$${amount.toLocaleString('en-AU', { minimumFractionDigits: amount % 1 !== 0 ? 2 : 0 })}`;
}

function CellValue({ value }: { value: ComparisonCellValue }) {
  switch (value.type) {
    case 'price':
      return (
        <Typography variant="body2" sx={{ fontWeight: 600, color: 'text.primary' }}>
          {formatPrice(value.amount)}
        </Typography>
      );
    case 'allowance':
      return (
        <Typography variant="body2" sx={{ fontWeight: 600, color: 'text.primary' }}>
          {formatPrice(value.amount)}*
        </Typography>
      );
    case 'complimentary':
      return (
        <Box sx={{ display: 'inline-flex', alignItems: 'center', gap: 0.5 }}>
          <CheckCircleOutlineIcon
            sx={{ fontSize: 16, color: 'var(--fa-color-feedback-success)' }}
            aria-hidden
          />
          <Typography
            variant="body2"
            sx={{ color: 'var(--fa-color-feedback-success)', fontWeight: 500 }}
          >
            Complimentary
          </Typography>
        </Box>
      );
    case 'included':
      return (
        <Box sx={{ display: 'inline-flex', alignItems: 'center', gap: 0.5 }}>
          <CheckCircleOutlineIcon
            sx={{ fontSize: 16, color: 'var(--fa-color-feedback-success)' }}
            aria-hidden
          />
          <Typography
            variant="body2"
            sx={{ color: 'var(--fa-color-feedback-success)', fontWeight: 500 }}
          >
            Included
          </Typography>
        </Box>
      );
    case 'poa':
      return (
        <Typography variant="caption" color="text.secondary" sx={{ fontStyle: 'italic' }}>
          Price On Application
        </Typography>
      );
    case 'unknown':
      return (
        <Badge color="default" variant="soft" size="small">
          Unknown
        </Badge>
      );
    case 'unavailable':
      return (
        <Typography variant="body2" sx={{ color: 'var(--fa-color-neutral-400)' }}>
          —
        </Typography>
      );
  }
}

function buildMergedSections(
  packages: ComparisonPackage[],
): { heading: string; items: { name: string; info?: string }[] }[] {
  const sectionMap = new Map<string, { name: string; info?: string }[]>();
  const sectionOrder: string[] = [];

  for (const pkg of packages) {
    if (pkg.itemizedAvailable === false) continue;
    for (const section of pkg.sections) {
      if (!sectionMap.has(section.heading)) {
        sectionMap.set(section.heading, []);
        sectionOrder.push(section.heading);
      }
      const existing = sectionMap.get(section.heading)!;
      for (const item of section.items) {
        if (!existing.some((e) => e.name === item.name)) {
          existing.push({ name: item.name, info: item.info });
        }
      }
    }
  }

  return sectionOrder.map((heading) => ({
    heading,
    items: sectionMap.get(heading) ?? [],
  }));
}

function lookupValue(
  pkg: ComparisonPackage,
  sectionHeading: string,
  itemName: string,
): ComparisonCellValue {
  if (pkg.itemizedAvailable === false) return { type: 'unavailable' };
  const section = pkg.sections.find((s) => s.heading === sectionHeading);
  if (!section) return { type: 'unavailable' };
  const item = section.items.find((i) => i.name === itemName);
  if (!item) return { type: 'unavailable' };
  return item.value;
}

/** Section heading with left accent border */
function SectionHeading({ children }: { children: React.ReactNode }) {
  return (
    <Box
      sx={{
        bgcolor: 'var(--fa-color-surface-subtle)',
        px: 3,
        py: 2.5,
        borderLeft: '3px solid',
        borderLeftColor: 'var(--fa-color-brand-500)',
      }}
    >
      <Typography variant="h6" component="h3">
        {children}
      </Typography>
    </Box>
  );
}

/** Reusable bordered table wrapper */
const tableSx = {
  display: 'grid',
  border: '1px solid',
  borderColor: 'divider',
  borderRadius: 'var(--fa-card-border-radius-default)',
  overflow: 'hidden',
  bgcolor: 'background.paper',
};

// ─── Component ──────────────────────────────────────────────────────────────

/**
 * Side-by-side package comparison table for the FA design system.
 *
 * Info card in top-left column, floating verified badges above cards,
 * section tables with left accent borders, no reviews table (rating in cards).
 *
 * Desktop only — ComparisonPage handles the mobile card view.
 */
export const ComparisonTable = React.forwardRef<HTMLDivElement, ComparisonTableProps>(
  ({ packages, onArrange, onRemove, sx }, ref) => {
    const colCount = packages.length + 1;
    const mergedSections = buildMergedSections(packages);
    const gridCols = `minmax(220px, 280px) repeat(${packages.length}, minmax(200px, 1fr))`;
    const minW = packages.length > 3 ? 960 : packages.length > 2 ? 800 : 600;

    return (
      <Box
        ref={ref}
        role="table"
        aria-label="Package comparison"
        sx={[
          {
            display: { xs: 'none', md: 'block' },
            overflowX: 'auto',
          },
          ...(Array.isArray(sx) ? sx : [sx]),
        ]}
      >
        <Box sx={{ minWidth: minW }}>
          {/* ── Package header cards ── */}
          <Box
            role="row"
            sx={{
              display: 'grid',
              gridTemplateColumns: gridCols,
              gap: 2,
              mb: 4,
              alignItems: 'stretch',
              pt: 3, // Room for floating verified badges
            }}
          >
            {/* Info card — stretches to match package card height, text at top */}
            <Card
              role="columnheader"
              variant="elevated"
              padding="default"
              sx={{
                bgcolor: 'var(--fa-color-surface-subtle)',
                alignSelf: 'stretch',
                display: 'flex',
                flexDirection: 'column',
                justifyContent: 'flex-start',
                border: 'none',
                boxShadow: 'none',
              }}
            >
              <Typography variant="label" sx={{ fontWeight: 700, display: 'block', mb: 1 }}>
                Package Comparison
              </Typography>
              <Typography
                variant="body2"
                color="text.secondary"
                sx={{ lineHeight: 1.5, display: 'block' }}
              >
                Review and compare features side-by-side to find the right fit.
              </Typography>
            </Card>

            {/* Package cards */}
            {packages.map((pkg) => (
              <Box
                key={pkg.id}
                role="columnheader"
                aria-label={pkg.isRecommended ? `${pkg.name} (Recommended)` : pkg.name}
                sx={{
                  position: 'relative',
                  overflow: 'visible',
                  display: 'flex',
                  flexDirection: 'column',
                }}
              >
                {/* Floating verified badge — overlaps card top edge */}
                {pkg.provider.verified && (
                  <Badge
                    color="brand"
                    variant="soft"
                    size="small"
                    icon={<VerifiedOutlinedIcon sx={{ fontSize: 14 }} />}
                    sx={{
                      position: 'absolute',
                      top: -12,
                      left: '50%',
                      transform: 'translateX(-50%)',
                      zIndex: 1,
                      boxShadow: '0 1px 3px rgba(0,0,0,0.1)',
                    }}
                  >
                    Verified
                  </Badge>
                )}

                <Card
                  variant="outlined"
                  selected={pkg.isRecommended}
                  padding="none"
                  sx={{ overflow: 'hidden', flex: 1, display: 'flex', flexDirection: 'column' }}
                >
                  {pkg.isRecommended && (
                    <Box
                      sx={{ bgcolor: 'var(--fa-color-brand-600)', py: 0.75, textAlign: 'center' }}
                    >
                      <Typography
                        variant="labelSm"
                        sx={{
                          color: 'var(--fa-color-white)',
                          fontWeight: 600,
                          letterSpacing: '0.05em',
                          textTransform: 'uppercase',
                        }}
                      >
                        Recommended
                      </Typography>
                    </Box>
                  )}

                  <Box
                    sx={{
                      display: 'flex',
                      flexDirection: 'column',
                      alignItems: 'center',
                      textAlign: 'center',
                      px: 2.5,
                      py: 2.5,
                      pt: pkg.provider.verified ? 3 : 2.5,
                      gap: 0.5,
                      flex: 1,
                    }}
                  >
                    {/* Provider name (truncated with tooltip) */}
                    <Tooltip
                      title={pkg.provider.name}
                      arrow
                      placement="top"
                      disableHoverListener={pkg.provider.name.length < 24}
                    >
                      <Typography
                        variant="label"
                        sx={{
                          fontWeight: 600,
                          overflow: 'hidden',
                          textOverflow: 'ellipsis',
                          whiteSpace: 'nowrap',
                          maxWidth: '100%',
                        }}
                      >
                        {pkg.provider.name}
                      </Typography>
                    </Tooltip>

                    {/* Location */}
                    <Typography variant="caption" color="text.secondary">
                      {pkg.provider.location}
                    </Typography>

                    {/* Rating */}
                    {pkg.provider.rating != null && (
                      <Box sx={{ display: 'inline-flex', alignItems: 'center', gap: 0.5 }}>
                        <StarRoundedIcon
                          sx={{ fontSize: 16, color: 'var(--fa-color-brand-500)' }}
                          aria-hidden
                        />
                        <Typography variant="body2" color="text.secondary">
                          {pkg.provider.rating}
                          {pkg.provider.reviewCount != null && ` (${pkg.provider.reviewCount})`}
                        </Typography>
                      </Box>
                    )}

                    <Divider sx={{ width: '100%', my: 1 }} />

                    <Typography variant="h6" component="p">
                      {pkg.name}
                    </Typography>

                    <Typography variant="caption" color="text.secondary" sx={{ mt: 0.5 }}>
                      Total package price
                    </Typography>
                    <Typography variant="h5" sx={{ color: 'primary.main', fontWeight: 700 }}>
                      {formatPrice(pkg.price)}
                    </Typography>

                    {/* Spacer pushes CTA to bottom across all cards */}
                    <Box sx={{ flex: 1 }} />

                    <Button
                      variant={pkg.provider.verified ? 'contained' : 'soft'}
                      color={pkg.provider.verified ? 'primary' : 'secondary'}
                      size="medium"
                      onClick={() => onArrange(pkg.id)}
                      sx={{ mt: 1.5, px: 4 }}
                    >
                      {pkg.provider.verified ? 'Make Arrangement' : 'Make Enquiry'}
                    </Button>

                    {!pkg.isRecommended && (
                      <Link
                        component="button"
                        variant="body2"
                        color="text.secondary"
                        underline="hover"
                        onClick={() => onRemove(pkg.id)}
                        sx={{ mt: 0.5 }}
                      >
                        Remove
                      </Link>
                    )}
                  </Box>
                </Card>
              </Box>
            ))}
          </Box>

          {/* ── Section tables (each separate with left accent headings) ── */}
          {mergedSections.map((section) => (
            <Box key={section.heading} sx={{ ...tableSx, gridTemplateColumns: gridCols, mb: 3 }}>
              <Box role="row" sx={{ gridColumn: `1 / ${colCount + 1}` }}>
                <SectionHeading>{section.heading}</SectionHeading>
              </Box>

              {section.items.map((item) => (
                <Box
                  key={item.name}
                  role="row"
                  sx={{
                    gridColumn: `1 / ${colCount + 1}`,
                    display: 'grid',
                    gridTemplateColumns: 'subgrid',
                    transition: 'background-color 0.15s ease',
                    '&:hover': { bgcolor: 'var(--fa-color-brand-50)' },
                  }}
                >
                  <Box
                    role="cell"
                    sx={{
                      display: 'flex',
                      alignItems: 'center',
                      gap: 0.5,
                      px: 3,
                      py: 2,
                      borderTop: '1px solid',
                      borderColor: 'divider',
                    }}
                  >
                    <Typography variant="body2" color="text.secondary" sx={{ minWidth: 0 }}>
                      {item.name}
                    </Typography>
                    {item.info && (
                      <Tooltip title={item.info} arrow placement="top">
                        <InfoOutlinedIcon
                          aria-label={`More information about ${item.name}`}
                          sx={{
                            fontSize: 14,
                            color: 'var(--fa-color-neutral-400)',
                            cursor: 'help',
                            flexShrink: 0,
                          }}
                        />
                      </Tooltip>
                    )}
                  </Box>

                  {packages.map((pkg) => (
                    <Box
                      key={pkg.id}
                      role="cell"
                      sx={{
                        display: 'flex',
                        alignItems: 'center',
                        justifyContent: 'center',
                        px: 2,
                        py: 2,
                        borderTop: '1px solid',
                        borderColor: 'divider',
                        borderLeft: '1px solid',
                        borderLeftColor: 'divider',
                      }}
                    >
                      <CellValue value={lookupValue(pkg, section.heading, item.name)} />
                    </Box>
                  ))}
                </Box>
              ))}
            </Box>
          ))}

          {packages.some((p) => p.itemizedAvailable === false) && mergedSections.length > 0 && (
            <Typography variant="caption" color="text.secondary" sx={{ fontStyle: 'italic' }}>
              * Some providers have not provided an itemised pricing breakdown. Their items are
              shown as "—" above.
            </Typography>
          )}
        </Box>
      </Box>
    );
  },
);

ComparisonTable.displayName = 'ComparisonTable';
export default ComparisonTable;