import type { ReportDocumentV2 } from "./personal-report-contract";
import { reportChartExportSvg } from "./report-chart-export";
import { buildLongformOutline, personalReportMarkdownFilename } from "./personal-report-longform-outline";
import { chartAriaLabel, parseReportChartBlock, stripReportChartBlocks, toNorthIndianChart, type ReportChartBlock } from "./report-chart-block";
import type { ReportFactTable } from "./report-fact-table-schema";
import { factCellText, FACT_STATUS_LABELS } from "./report-fact-table-display";
import { projectOrdinaryReportMarkdown } from "./report-public-projection";

export type ReportExportBlock = Readonly<{
  id: string;
  group: "body" | "chart" | "table";
  title: string;
  text: string;
  chars: number;
}>;
export type ReportExportPreset = "common" | "charts" | "tables";

export function chartBlockText(block: ReportChartBlock): string {
  const chart = toNorthIndianChart(block);
  return `#### ${chartAriaLabel(block.id)}\n\n${chart.houses.map(house =>
    `- 第 ${house.houseNumber} 宫 · ${house.sign}：${house.occupants.join("、") || "—"}`,
  ).join("\n")}`;
}

function tableCell(value: ReportFactTable["rows"][number]["cells"][number]): string {
  return factCellText(value).replace(/\\/g, "\\\\").replace(/\|/g, "\\|").replace(/\r?\n/g, "<br>");
}

function tableGrid(table: Pick<ReportFactTable, "columns" | "rows">): string {
  if (!table.rows.length) return "";
  return [
    `| ${table.columns.map(tableCell).join(" | ")} |`,
    `| ${table.columns.map(() => "---").join(" | ")} |`,
    ...table.rows.map(row => `| ${row.cells.map(tableCell).join(" | ")} |`),
  ].join("\n");
}

/** Same labels, precision, missing values and subtables as ReportFactTables; no provenance paths. */
export function factTableToMarkdown(group: ReportFactTable): string {
  return projectOrdinaryReportMarkdown([
    `## ${group.title}`,
    FACT_STATUS_LABELS[group.claimStatus],
    group.note,
    tableGrid(group),
    ...(group.subtables ?? []).flatMap(table => [`### ${table.title}`, table.note, tableGrid(table)]),
  ].filter(Boolean).join("\n\n"));
}

export function buildReportExportBlocks({ markdown, charts = [], factTables = [] }: {
  markdown: string;
  charts?: ReportDocumentV2["charts"];
  factTables?: readonly ReportFactTable[];
}): ReportExportBlock[] {
  const projected = projectOrdinaryReportMarkdown(markdown);
  const outline = buildLongformOutline(projected);
  const blocks: ReportExportBlock[] = [];
  function add(id: string, group: ReportExportBlock["group"], title: string, text: string) {
    blocks.push({ id, group, title, text, chars: Array.from(text).length });
  }
  // sourcePreamble/sourceMarkdown are the outline's lossless counterparts. The reader's
  // leadMarkdown also contains lifted summaries: using it here duplicates/reorders prose.
  if (outline.sourcePreamble) add("body:lead", "body", "摘要", stripReportChartBlocks(outline.sourcePreamble));
  for (const section of outline.sections) {
    add(`body:${section.id}`, "body", section.title, stripReportChartBlocks(section.sourceMarkdown));
  }
  const chartIds = new Set<string>();
  for (const match of projected.matchAll(/```jyotish-chart\r?\n([\s\S]*?)```/g)) {
    const block = parseReportChartBlock(match[1]);
    if (!block) continue;
    const occurrence = blocks.filter(item => item.group === "chart" && item.id.startsWith(`chart:${block.id}:`)).length + 1;
    chartIds.add(block.id);
    // Only the immediately preceding SVG belongs to this occurrence (D9 may repeat).
    // The public projection has already rejected unsafe SVG; never recover raw HTML.
    const preceding = projected.slice(0, match.index);
    const svg = preceding.match(/(<svg\b[^>]*>[\s\S]*?<\/svg>)\s*$/i)?.[1];
    const safeSvg = svg?.slice(svg.lastIndexOf("<svg"))
      ?? reportChartExportSvg(toNorthIndianChart(block), chartAriaLabel(block.id));
    add(`chart:${block.id}:${occurrence}`, "chart", chartAriaLabel(block.id), `${chartBlockText(block)}\n\n${safeSvg}`);
  }
  // New structured layers can contain charts absent from old Markdown. Never invent
  // missing houses, nor duplicate a chart already supplied by a validated fence.
  for (const chart of charts) {
    if (chartIds.has(chart.id) || !chart.houses.some(house => house.occupants.length)) continue;
    chartIds.add(chart.id);
    const title = chartAriaLabel(chart.id);
    const text = `#### ${title}\n\n${chart.houses.map(house =>
      `- 第 ${house.houseNumber} 宫 · ${house.sign}：${house.occupants.join("、") || "—"}`,
    ).join("\n")}`;
    add(`chart:${chart.id}`, "chart", title, projectOrdinaryReportMarkdown(`${text}\n\n${reportChartExportSvg(chart, title)}`));
  }
  for (const table of factTables) add(`table:${table.id}`, "table", table.title, factTableToMarkdown(table));
  return blocks;
}

export function joinExportBlocks(blocks: readonly ReportExportBlock[]): string {
  // Preserve source boundaries (including CRLF/trailing whitespace) for D5. All
  // body slices are in outline order; stripping once more handles boundary blank runs.
  const body = stripReportChartBlocks(blocks.filter(block => block.group === "body").map(block => block.text).join(""));
  const added = blocks.filter(block => block.group !== "body").map(block => block.text).join("\n\n");
  return body && added ? `${body}\n\n${added}` : body || added;
}

export function presetSelection(preset: ReportExportPreset, blocks: readonly ReportExportBlock[]): Set<string> {
  const group = { common: "body", charts: "chart", tables: "table" }[preset];
  return new Set(blocks.filter(block => block.group === group).map(block => block.id));
}

/** downloadMarkdownReport appends .md; returning an extension here would duplicate it. */
export function exportFilename(reportDate: string | null | undefined, isFull: boolean): string {
  return `${personalReportMarkdownFilename(reportDate)}${isFull ? "" : "-节选"}`;
}

/** UTF-8 bytes of exactly what the download would contain; not a per-character guess. */
export function exportByteSize(blocks: readonly ReportExportBlock[]): number {
  return blocks.length ? new TextEncoder().encode(joinExportBlocks(blocks)).length : 0;
}

/** 「约 186 KB」 / 「约 1.4 MB」; under 1 KB still reads 「约 1 KB」 so it never says 0. */
export function formatExportSize(bytes: number): string {
  if (bytes >= 1024 * 1024) return `约 ${(bytes / (1024 * 1024)).toFixed(1)} MB`;
  return `约 ${Math.max(1, Math.round(bytes / 1024))} KB`;
}