//
//  extractor.js — Prisme
//
//  Author: Simon-Pierre Boucher <contact@spboucher.ai>
//
//  Deterministic DOM extraction (Distiller step 1, CLAUDE.md §4).
//  Injected at documentEnd; defines functions only — nothing runs until
//  the app asks. Never sends raw HTML anywhere: produces a compact block
//  list with DOM paths so every derived element can be traced back.

(function () {
  "use strict";

  var SKIP_TAGS = {
    SCRIPT: 1, STYLE: 1, NOSCRIPT: 1, IFRAME: 1, SVG: 1, CANVAS: 1,
    NAV: 1, FOOTER: 1, ASIDE: 1, FORM: 1, BUTTON: 1, SELECT: 1, TEMPLATE: 1
  };
  var NOISE_RE = /(^|[-_ ])(ad|ads|advert|promo|banner|cookie|consent|gdpr|newsletter|popup|paywall|subscribe|share|social|sidebar|related|comment)s?([-_ ]|$)/i;

  function isNoise(el) {
    var probe = (el.className && String(el.className)) + " " + (el.id || "");
    return NOISE_RE.test(probe);
  }

  function isHidden(el) {
    return el.getClientRects && el.getClientRects().length === 0;
  }

  function linkDensity(el) {
    var text = el.textContent || "";
    if (text.length === 0) return 1;
    var linked = 0;
    var anchors = el.getElementsByTagName("a");
    for (var i = 0; i < anchors.length; i++) linked += (anchors[i].textContent || "").length;
    return linked / text.length;
  }

  function domPath(el) {
    var path = [];
    var node = el;
    while (node && node !== document.body) {
      var parent = node.parentElement;
      if (!parent) break;
      path.unshift(Array.prototype.indexOf.call(parent.children, node));
      node = parent;
    }
    return path.join("/");
  }

  function clean(text) {
    return text.replace(/\s+/g, " ").trim();
  }

  function blockFor(el) {
    var tag = el.tagName;
    if (/^H[1-6]$/.test(tag)) return { kind: "heading", level: parseInt(tag[1], 10) };
    if (tag === "P") return { kind: "paragraph", level: 0 };
    if (tag === "LI") return { kind: "listItem", level: 0 };
    if (tag === "BLOCKQUOTE") return { kind: "quote", level: 0 };
    if (tag === "PRE") return { kind: "code", level: 0 };
    if (tag === "TABLE") return { kind: "table", level: 0 };
    if (tag === "FIGCAPTION") return { kind: "caption", level: 0 };
    return null;
  }

  // Depth-first walk. A captured block's subtree is not descended into, so
  // nested text is never emitted twice.
  function walk(el, blocks, maxBlocks) {
    if (blocks.length >= maxBlocks) return;
    if (SKIP_TAGS[el.tagName] || isNoise(el) || isHidden(el)) return;

    var spec = blockFor(el);
    if (spec) {
      if (spec.kind === "heading" || linkDensity(el) <= 0.5) {
        var text = clean(spec.kind === "table" ? (el.innerText || "") : (el.textContent || ""));
        if (text.length >= (spec.kind === "heading" ? 2 : 25)) {
          if (text.length > 2000) text = text.slice(0, 2000) + "…";
          blocks.push({ kind: spec.kind, level: spec.level, text: text, domPath: domPath(el) });
        }
      }
      return;
    }

    for (var i = 0; i < el.children.length; i++) {
      walk(el.children[i], blocks, maxBlocks);
    }
  }

  window.__prismeExtract = function (maxBlocks) {
    var blocks = [];
    walk(document.body, blocks, maxBlocks || 400);
    return JSON.stringify({
      title: clean(document.title || ""),
      lang: document.documentElement.lang || null,
      blocks: blocks
    });
  };

  // Current text selection with its source anchor and section context —
  // everything an excerpt needs (CLAUDE.md §5, "L'extrait", P0).
  window.__prismeSelection = function () {
    var sel = document.getSelection();
    if (!sel || sel.isCollapsed) return null;
    var text = sel.toString().replace(/\s+/g, " ").trim();
    if (!text) return null;
    if (text.length > 2000) text = text.slice(0, 2000) + "…";

    var node = sel.anchorNode;
    var el = node ? (node.nodeType === 1 ? node : node.parentElement) : null;
    var path = el ? domPath(el) : null;

    // Nearest heading above the selection gives the section context.
    var heading = null;
    var probe = el;
    while (probe && probe !== document.body && !heading) {
      var sibling = probe;
      while ((sibling = sibling.previousElementSibling)) {
        if (/^H[1-6]$/.test(sibling.tagName)) { heading = sibling.textContent; break; }
      }
      probe = probe.parentElement;
    }

    return JSON.stringify({
      text: text,
      domPath: path,
      section: heading ? clean(heading) : null
    });
  };

  window.__prismeScrollTo = function (path) {
    var node = document.body;
    if (path) {
      var parts = path.split("/");
      for (var i = 0; i < parts.length && node; i++) {
        node = node.children[parseInt(parts[i], 10)];
      }
    }
    if (node && node.scrollIntoView) {
      node.scrollIntoView({ behavior: "smooth", block: "start" });
      return true;
    }
    return false;
  };
})();