/**
 * quoted-before-service — quote-level roll-up of "have we priced this
 * before, and what did it go out at?".
 *
 * ## Why this exists
 *
 * The office does mining supply. When a mine puts a spot out to
 * tender, SEVERAL engineering companies each ask us to price the same
 * item list, because they're all bidding for it. Before pricing the
 * new one, the operator wants to see what the earlier quote went out
 * at — partly for consistency, partly to give the loyal client the
 * better number.
 *
 * The per-LINE answer already exists: `populateItemIntel` in
 * `item-intel-service.ts` powers the ⓘ popover on each row of the
 * process page and returns `recent_quote` (prior quote number,
 * company, selling price, days ago). This service does NOT re-implement
 * any of that matching — it calls the same function per line and rolls
 * the results up to the QUOTE level, so the operator gets one panel
 * instead of clicking ⓘ on every row.
 *
 * ## What the roll-up adds over the per-line popover
 *
 *   - "N of your M lines have been quoted before" at a glance.
 *   - `relatedQuotes`: prior quotes ranked by HOW MANY of this quote's
 *     lines they also carried. A prior quote covering 5 of 5 lines is
 *     almost certainly the same tender from a different bidder; one
 *     covering 1 of 5 is just a shared commodity line.
 *
 * ## Deliberately not date-filtered
 *
 * The `quotes` collection has no trustworthy per-quote timestamp — a
 * migration stamped `created` on 94% of rows and a later backfill
 * stamped `updated` on 95%, while `quote_date` and `email_received_at`
 * are effectively empty. Any recency cutoff here would therefore be
 * arbitrary. The underlying intel ranks by match score and recency of
 * the underlying row, which is the honest signal available.
 */

import { getAdminPocketBase } from "@/lib/server/pocketbase-admin";
import { populateItemIntel } from "@/lib/server/item-intel-service";
import type { ItemIntelQuoteRow } from "@/lib/types";

/** One line of the target quote plus the prior quotes that carried it. */
export interface QuotedBeforeLine {
  itemId: string;
  description: string;
  quantity: number;
  /** Prior quote rows for this line, best match first. Empty when this
   *  line has never been quoted before. */
  priorQuotes: ItemIntelQuoteRow[];
}

/** A prior quote, rolled up across every line of the target it matched. */
export interface QuotedBeforeRelatedQuote {
  quoteId: string;
  quoteNumber: string;
  status: string;
  company: string;
  customerName: string;
  /** How many of the TARGET quote's lines this prior quote also had.
   *  The ranking signal — high means "same list, different bidder". */
  matchedLines: number;
  /** Summed selling_price × quantity across just the matched lines.
   *  0 means the prior quote's matched lines were never priced — the
   *  UI must say "unpriced" rather than render R0.00, which reads as
   *  "we quoted it at zero". */
  matchedValue: number;
  /** True when at least one matched line on the prior quote carried a
   *  price. Distinguishes "priced at R0" from "never priced". */
  hasPrice: boolean;
  /** Age of the most recent matched line on that quote. */
  daysAgo: number;
  /**
   * Best per-line match score behind this roll-up (0-1), straight from
   * the underlying Item Intel ranking. The intel threshold is 0.5, so
   * anything here is a *candidate* rather than a certainty — a 0.5-0.6
   * hit is often a different product sharing tokens. Surfaced so the
   * operator can tell a same-part match from a loose one instead of
   * trusting every row equally.
   */
  matchConfidence: number;
}

export interface QuotedBeforeResult {
  quoteId: string;
  /** Lines on the target quote that were checked. */
  totalLines: number;
  /** How many of those had at least one prior quote. */
  matchedLines: number;
  lines: QuotedBeforeLine[];
  /** Prior quotes ranked by `matchedLines` desc, then recency. */
  relatedQuotes: QuotedBeforeRelatedQuote[];
}

/**
 * How many line-intel computations run at once. Each `populateItemIntel`
 * call fans out to several PB queries, so an unbounded `Promise.all`
 * over a 20-line quote would hammer PB. Measured ~400-650ms per line,
 * so a batch of 5 keeps a typical 3-10 line quote comfortably inside a
 * couple of seconds.
 */
const INTEL_CONCURRENCY = 5;

/**
 * Cap on lines checked per request. Quotes with more lines than this
 * are truncated rather than left to run for a minute — the roll-up is
 * an at-a-glance aid, and the per-line ⓘ popover is still there for
 * the remainder.
 */
const MAX_LINES_CHECKED = 40;

export async function getQuotedBeforeForQuote(
  quoteId: string,
): Promise<QuotedBeforeResult> {
  const pb = await getAdminPocketBase();
  pb.autoCancellation(false);

  // `moved_to_quote` lines have been split off to another quote and
  // aren't part of this one any more — same exclusion the intel
  // batch path (`populateIntelForParent`) uses.
  const items = await pb.collection("quote_items").getFullList<{
    id: string;
    description?: string;
    quantity?: number;
  }>({
    filter: `quote = "${quoteId.replace(/"/g, '\\"')}" && (moved_to_quote = null || moved_to_quote = "")`,
    fields: "id,description,quantity",
    sort: "created",
  });

  const checked = items.slice(0, MAX_LINES_CHECKED);
  const lines: QuotedBeforeLine[] = [];

  for (let i = 0; i < checked.length; i += INTEL_CONCURRENCY) {
    const batch = checked.slice(i, i + INTEL_CONCURRENCY);
    const settled = await Promise.all(
      batch.map(async (item) => {
        try {
          // `write: false` — this is a read-only panel. Persisting the
          // blob on every page view would mutate rows the operator
          // only looked at.
          const intel = await populateItemIntel(item.id, "quote_items", {
            write: false,
          });
          return {
            itemId: item.id,
            description: item.description || "",
            quantity: Number(item.quantity) || 1,
            priorQuotes: intel.recent_quote ?? [],
          };
        } catch {
          // One bad line shouldn't sink the whole panel.
          return {
            itemId: item.id,
            description: item.description || "",
            quantity: Number(item.quantity) || 1,
            priorQuotes: [] as ItemIntelQuoteRow[],
          };
        }
      }),
    );
    lines.push(...settled);
  }

  // Roll up by prior quote. A quote that shows up against many of the
  // target's lines is the interesting one.
  const related = new Map<string, QuotedBeforeRelatedQuote>();
  for (const line of lines) {
    // Dedupe within a line: if two of the target's own rows matched the
    // same prior quote, that prior quote still only covered this line
    // once.
    const seenThisLine = new Set<string>();
    for (const prior of line.priorQuotes) {
      if (!prior.quote_id || seenThisLine.has(prior.quote_id)) continue;
      seenThisLine.add(prior.quote_id);
      const existing = related.get(prior.quote_id);
      const unitPrice = Number(prior.selling_price) || 0;
      const lineValue = unitPrice * (Number(prior.quantity) || 1);
      const score = Number(prior.score) || 0;
      if (existing) {
        existing.matchedLines += 1;
        existing.matchedValue += lineValue;
        existing.hasPrice = existing.hasPrice || unitPrice > 0;
        existing.daysAgo = Math.min(existing.daysAgo, prior.days_ago ?? 0);
        existing.matchConfidence = Math.max(existing.matchConfidence, score);
      } else {
        related.set(prior.quote_id, {
          quoteId: prior.quote_id,
          quoteNumber: prior.quote_number || "",
          status: prior.quote_status || "",
          company: prior.company || "",
          customerName: prior.customer_name || "",
          matchedLines: 1,
          matchedValue: lineValue,
          hasPrice: unitPrice > 0,
          daysAgo: prior.days_ago ?? 0,
          matchConfidence: score,
        });
      }
    }
  }

  // Most-overlapping first (same list = same tender), then best match
  // quality, then most recent. Confidence outranks recency so a strong
  // older match isn't buried under a loose recent one.
  const relatedQuotes = [...related.values()].sort(
    (a, b) =>
      b.matchedLines - a.matchedLines ||
      b.matchConfidence - a.matchConfidence ||
      a.daysAgo - b.daysAgo,
  );

  return {
    quoteId,
    totalLines: checked.length,
    matchedLines: lines.filter((l) => l.priorQuotes.length > 0).length,
    lines,
    relatedQuotes,
  };
}