/*
 * Skill Forge — browser port of skillforge.py.
 * Pure functions; depends only on window.jsyaml (js-yaml UMD).
 * Kept deliberately in lockstep with the Python module so behaviour matches.
 */
(function (global) {
  "use strict";

  const NAME_RE = /^[a-z0-9]+(?:-[a-z0-9]+)*$/;
  const NAME_MAX = 64;
  const DESC_MAX = 1024;
  const KNOWN_KEYS = new Set([
    "name", "description", "license", "allowed-tools", "allowed_tools",
    "metadata", "version", "compatible-with", "compatible_with",
  ]);
  const TRIGGER_CUES = ["use when", "use this", "when the user", "when asked",
    "trigger", "for tasks", "helps with", "invoke when"];

  function Report() {
    this.ok = true; this.errors = []; this.warnings = []; this.info = [];
  }
  Report.prototype.err = function (m) { this.errors.push(m); this.ok = false; };
  Report.prototype.warn = function (m) { this.warnings.push(m); };
  Report.prototype.note = function (m) { this.info.push(m); };
  Report.prototype.asMarkdown = function () {
    const head = this.ok ? "## ✅ Valid skill" : "## ❌ Invalid skill";
    const out = [head, ""];
    [["Errors", this.errors, "🔴"],
     ["Warnings", this.warnings, "🟡"],
     ["Info", this.info, "🔵"]].forEach(function (t) {
      if (t[1].length) {
        out.push("**" + t[0] + "**");
        t[1].forEach(function (x) { out.push("- " + t[2] + " " + x); });
        out.push("");
      }
    });
    if (this.ok && !this.warnings.length) out.push("_No issues found._");
    return out.join("\n").trim();
  };

  function splitFrontmatter(text) {
    text = text.replace(/^/, "");
    if (!text.startsWith("---")) return [null, text];
    const m = text.match(/^---[ \t]*\r?\n([\s\S]*?)\r?\n---[ \t]*\r?\n?([\s\S]*)$/);
    if (!m) return [null, text];
    return [m[1], m[2]];
  }

  function validateSkill(skillMd) {
    const r = new Report();
    if (!skillMd || !skillMd.trim()) { r.err("File is empty."); return r; }

    const parts = splitFrontmatter(skillMd);
    const fmRaw = parts[0], body = parts[1];
    if (fmRaw === null) {
      r.err("No YAML frontmatter. SKILL.md must start with a '---' fenced block.");
      return r;
    }
    let fm;
    try { fm = global.jsyaml.load(fmRaw) || {}; }
    catch (e) { r.err("Frontmatter is not valid YAML: " + e.message); return r; }
    if (typeof fm !== "object" || Array.isArray(fm)) {
      r.err("Frontmatter must be a YAML mapping (key: value pairs)."); return r;
    }

    let name = fm.name;
    if (name === undefined || name === null || !String(name).trim()) {
      r.err("`name` is required in frontmatter.");
    } else {
      name = String(name).trim();
      if (name.length > NAME_MAX) r.err("`name` is " + name.length + " chars; keep it <= " + NAME_MAX + ".");
      if (!NAME_RE.test(name)) r.err("`name` must be kebab-case: lowercase letters, digits, single hyphens.");
    }

    let desc = fm.description;
    if (desc === undefined || desc === null || !String(desc).trim()) {
      r.err("`description` is required — it is how an agent decides to use the skill.");
    } else {
      desc = String(desc).trim();
      if (desc.length > DESC_MAX) r.err("`description` is " + desc.length + " chars; keep it <= " + DESC_MAX + ".");
      if (desc.length < 40) r.warn("`description` is very short; say what the skill does *and* when to use it.");
      const low = desc.toLowerCase();
      if (!TRIGGER_CUES.some(function (c) { return low.indexOf(c) !== -1; }))
        r.warn("`description` has no explicit trigger ('Use when...'); agents may not fire it.");
    }

    if (!body.trim()) {
      r.err("Body is empty. Put the actual instructions after the frontmatter.");
    } else {
      if (!/^#{1,6}\s/m.test(body) && body.length > 400)
        r.warn("Long body with no Markdown headings; add structure for skimmability.");
      const links = body.match(/\[[^\]]*\]\(([^)]+)\)/g) || [];
      links.forEach(function (raw) {
        const link = raw.match(/\(([^)]+)\)/)[1];
        if (/^(https?:\/\/|#|mailto:)/.test(link)) return;
        if (link.startsWith("/"))
          r.warn("Absolute path link '" + link + "'; use a path relative to the skill folder.");
      });
    }

    const unknown = Object.keys(fm).filter(function (k) { return !KNOWN_KEYS.has(k); }).sort();
    if (unknown.length)
      r.note("Non-standard frontmatter keys (ignored by most hosts): " + unknown.join(", "));

    const at = fm["allowed-tools"] !== undefined ? fm["allowed-tools"] : fm.allowed_tools;
    if (at !== undefined && at !== null && !Array.isArray(at) && typeof at !== "string")
      r.warn("`allowed-tools` should be a list (or comma string) of tool names.");

    return r;
  }

  function lintDescription(description) {
    const r = new Report();
    const d = (description || "").trim();
    if (!d) { r.err("Empty description."); return r; }

    let score = 100;
    const low = d.toLowerCase();
    const n = d.length;

    if (n < 40) { score -= 35; r.warn("Too short (" + n + " chars). Aim for ~150–500."); }
    else if (n < 150) { score -= 10; r.warn("A bit short (" + n + " chars); add concrete trigger cases."); }
    else if (n > DESC_MAX) { score -= 30; r.err("Over the " + DESC_MAX + "-char limit (" + n + ")."); }
    else if (n > 700) { score -= 8; r.warn("Long (" + n + " chars); tighten to the essentials."); }

    if (!TRIGGER_CUES.some(function (c) { return low.indexOf(c) !== -1; })) {
      score -= 25;
      r.warn("No explicit trigger phrase. Add 'Use when the user...' with real examples.");
    }
    if (/^(this skill|a skill|the skill|this is)/.test(low)) {
      score -= 10;
      r.warn("Starts with 'This skill...'. Lead with the capability or the trigger.");
    }
    if (/\b(i|you|we|my|your)\b/.test(low)) {
      score -= 6;
      r.note("Uses first/second person; third-person reads better in a registry.");
    }
    const verbs = low.match(/\b(create|build|convert|review|audit|generate|analy[sz]e|extract|summari[sz]e|refactor|debug|validate|lint|format|deploy|test|search|fetch|translate|render|plan)\w*/g);
    if (!verbs) { score -= 12; r.warn("No action verbs; name what the skill *does*."); }

    if (/(e\.g\.|for example|such as|like )/.test(low)) r.note("Has examples — good for trigger matching.");
    else { score -= 8; r.warn("No examples. Concrete phrases ('e.g. \"redesign my landing page\"') help matching."); }

    score = Math.max(0, Math.min(100, score));
    const verdict = score >= 80 ? "strong" : score >= 55 ? "usable" : "weak";
    r.note("Trigger score: " + score + "/100 (" + verdict + ")");
    r.ok = score >= 55;
    r.score = score;
    return r;
  }

  function scaffoldSkill(name, description, whenToUse) {
    name = (name || "my-skill").trim().toLowerCase().replace(/ /g, "-").replace(/[^a-z0-9-]/g, "") || "my-skill";
    let desc = (description || "").split(/\s+/).filter(Boolean).join(" ");
    whenToUse = (whenToUse || "").trim();
    if (whenToUse) {
      if (desc.toLowerCase().indexOf("use when") === -1) {
        desc = desc
          ? desc + " Use when " + whenToUse.charAt(0).toLowerCase() + whenToUse.slice(1)
          : "Use when " + whenToUse;
      } else {
        desc = desc + " " + whenToUse;
      }
    }
    if (!desc) {
      desc = 'Describe what this skill does and the concrete situations that should ' +
             'trigger it, e.g. "Use when the user asks to ...".';
    }
    const title = name.replace(/-/g, " ").replace(/\b\w/g, function (c) { return c.toUpperCase(); });
    return "---\n" +
      "name: " + name + "\n" +
      "description: " + desc + "\n" +
      "---\n\n" +
      "# " + title + "\n\n" +
      "## When to use this skill\n\n" +
      "- Trigger 1 — a concrete user request this handles.\n" +
      "- Trigger 2 — another phrasing or situation.\n" +
      "- Do **not** use it for: <the near-miss cases that belong elsewhere>.\n\n" +
      "## Instructions\n\n" +
      "1. First step.\n2. Second step.\n3. What to hand back to the user.\n\n" +
      "## Notes\n\n" +
      "- Edge cases, gotchas, and links to bundled files (paths relative to this folder).\n";
  }

  global.SkillForge = { splitFrontmatter, validateSkill, lintDescription, scaffoldSkill };
})(typeof window !== "undefined" ? window : globalThis);