#!/usr/bin/env python3
"""
Comment on newly opened issues with possible duplicates and triage hints.

This script is run by a GitHub Actions workflow when a new issue is opened. It:
1. Checks eligibility (bug/crash type or untyped, non-staff author)
2. Detects relevant areas using Claude + the area label taxonomy
3. Parses known "duplicate magnets" from tracking issue #46355
4. Searches for similar issues — open (last 60 days) and recently closed (last 30 days)
5. Asks Claude to sort open candidates into likely and possible duplicates, and
   surface recently closed issues that may be useful triage context
6. Posts a comment if anything is found: a user-facing duplicate alert for likely
   duplicates, and/or a collapsed triager-facing section for possible duplicates
   and recently closed related issues

Requires:
    requests (pip install requests)

Usage:
    python github-check-new-issue-for-duplicates.py <issue_number>

Environment variables:
    GITHUB_TOKEN       - GitHub token (org members: read, issues: read & write)
    ANTHROPIC_API_KEY  - Anthropic API key for Claude

"""

import argparse
import json
import os
import re
import sys
import time
from datetime import datetime, timedelta

import requests

GITHUB_API = "https://api.github.com"
REPO_OWNER = "zed-industries"
REPO_NAME = "zed"
TRACKING_ISSUE_NUMBER = 46355
STAFF_TEAM_SLUG = "staff"

# area prefixes to collapse in taxonomy (show summary instead of all sub-labels)
PREFIXES_TO_COLLAPSE = ["languages", "parity", "tooling"]

# stopwords to filter from title keyword searches (short words handled by len > 2 filter)
STOPWORDS = {
    "after", "all", "also", "and", "any", "but", "can't", "does", "doesn't",
    "don't", "for", "from", "have", "just", "not", "only", "some", "that",
    "the", "this", "when", "while", "with", "won't", "work", "working", "zed",
}

# HTTP statuses we'll retry on for GET requests
TRANSIENT_HTTP_STATUSES = {429, 500, 502, 503, 504}


def log(message):
    """Print to stderr so it doesn't interfere with JSON output on stdout."""
    print(message, file=sys.stderr)


def github_api_get(path, params=None):
    """Fetch JSON from the GitHub API, retrying transient failures. Raises on non-2xx status."""
    url = f"{GITHUB_API}/{path.lstrip('/')}"
    for attempt in range(3):
        try:
            response = requests.get(url, headers=GITHUB_HEADERS, params=params)
            response.raise_for_status()
            return response.json()
        except requests.RequestException as e:
            transient = isinstance(e, (requests.ConnectionError, requests.Timeout)) or (
                isinstance(e, requests.HTTPError) and e.response.status_code in TRANSIENT_HTTP_STATUSES
            )
            if not transient or attempt == 2:
                raise
            wait = 2 ** attempt
            log(f"  Transient GitHub API error ({e}); retrying in {wait}s")
            time.sleep(wait)


def github_search_issues(query, per_page=15):
    """Search issues, returning most recently created first."""
    params = {"q": query, "sort": "created", "order": "desc", "per_page": per_page}
    return github_api_get("/search/issues", params).get("items", [])


def check_team_membership(org, team_slug, username):
    """Check if user is an active member of a team."""
    try:
        data = github_api_get(f"/orgs/{org}/teams/{team_slug}/memberships/{username}")
        return data.get("state") == "active"
    except requests.HTTPError as e:
        if e.response.status_code == 404:
            return False
        raise


def post_comment(issue_number: int, body):
    url = f"{GITHUB_API.rstrip('/')}/repos/{REPO_OWNER}/{REPO_NAME}/issues/{issue_number}/comments"
    response = requests.post(url, headers=GITHUB_HEADERS, json={"body": body})
    response.raise_for_status()
    log(f"  Posted comment on #{issue_number}")


def build_comment(likely_duplicates, possible_duplicates, related_closed_issues):
    """Compose the full comment body. Returns empty string if there's nothing to post.

    The comment has two sections, each optional:
    - User-facing duplicate alert, rendered when likely_duplicates is non-empty.
    - Collapsed triage context, rendered when there are possible duplicates or
      related closed issues to surface for triagers.
    """
    sections = []

    if likely_duplicates:
        match_list = "\n".join(f"- #{m['number']}" for m in likely_duplicates)
        explanations = "\n\n".join(
            f"**#{m['number']}:** {m['explanation']}\n\n**Shared root cause:** {m['shared_root_cause']}"
            for m in likely_duplicates
        )
        sections.append(f"""This issue appears to be a duplicate of:

{match_list}

**If this is indeed a duplicate:**
Please close this issue and subscribe to the linked issue for updates (select "Close as not planned" → "Duplicate")

**If this is a different issue:**
No action needed. A maintainer will review this shortly.

<details>
<summary>Why were these issues selected?</summary>

{explanations}

</details>""")

    if possible_duplicates or related_closed_issues:
        parts = []
        if possible_duplicates:
            lines = [
                f"- #{m['number']} — {m['explanation']}\n"
                f"  - Possible shared root cause: {m['shared_root_cause']}"
                for m in possible_duplicates
            ]
            parts.append("**Possibly related open issues:**\n\n" + "\n".join(lines))
        if related_closed_issues:
            lines = [
                f"- #{m['number']} (closed as {m['state_reason']}) — {m['explanation']}"
                for m in related_closed_issues
            ]
            parts.append("**Recently closed, possibly related:**\n\n" + "\n".join(lines))
        body = "\n\n".join(parts)
        sections.append(f"""<details>
<summary>Additional recent context for triagers</summary>

{body}

</details>""")

    if not sections:
        return ""

    sections.append("---\n<sub>This is an automated analysis and might be incorrect.</sub>")
    return "\n\n".join(sections)


def call_claude(api_key, system, user_content, max_tokens=1024):
    """Send a message to Claude and return the text response. Raises on non-2xx status."""
    response = requests.post(
        "https://api.anthropic.com/v1/messages",
        headers={
            "x-api-key": api_key,
            "anthropic-version": "2023-06-01",
            "content-type": "application/json",
        },
        json={
            "model": "claude-sonnet-4-20250514",
            "max_tokens": max_tokens,
            "temperature": 0.0,
            "system": system,
            "messages": [{"role": "user", "content": user_content}],
        },
    )
    response.raise_for_status()
    data = response.json()

    usage = data.get("usage", {})
    log(f"  Token usage - Input: {usage.get('input_tokens', 'N/A')}, Output: {usage.get('output_tokens', 'N/A')}")

    content = data.get("content", [])
    if content and content[0].get("type") == "text":
        return content[0].get("text") or ""
    return ""


def fetch_issue(issue_number: int):
    """Fetch issue from GitHub and return as a dict."""
    log(f"Fetching issue #{issue_number}")

    issue_data = github_api_get(f"/repos/{REPO_OWNER}/{REPO_NAME}/issues/{issue_number}")
    issue = {
        "number": issue_number,
        "title": issue_data["title"],
        "body": issue_data.get("body") or "",
        "author": (issue_data.get("user") or {}).get("login") or "",
        "type": (issue_data.get("type") or {}).get("name"),
    }

    log(f"  Title: {issue['title']}\n  Type: {issue['type']}\n  Author: {issue['author']}")
    return issue


def should_skip(issue):
    """Check if issue should be skipped in duplicate detection process."""
    if issue["type"] and issue["type"] not in ["Bug", "Crash"]:
        log(f"  Skipping: issue type '{issue['type']}' is not blank and not a bug/crash report")
        return True

    if issue["author"] and check_team_membership(REPO_OWNER, STAFF_TEAM_SLUG, issue["author"]):
        log(f"  Skipping: author '{issue['author']}' is a {STAFF_TEAM_SLUG} member")
        return True

    return False


def fetch_area_labels():
    """Fetch area:* labels from the repository. Returns list of {name, description} dicts."""
    log("Fetching area labels")

    labels = []
    page = 1
    while page_labels := github_api_get(
        f"/repos/{REPO_OWNER}/{REPO_NAME}/labels",
        params={"per_page": 100, "page": page},
    ):
        labels.extend(page_labels)
        page += 1

    # label["name"][5:] removes the "area:" prefix
    area_labels = [
        {"name": label["name"][5:], "description": label.get("description") or ""}
        for label in labels
        if label["name"].startswith("area:")
    ]

    log(f"  Found {len(area_labels)} area labels")
    return area_labels


def format_taxonomy_for_claude(area_labels):
    """Format area labels into a string for Claude, collapsing certain prefixes."""
    lines = set()

    for area in area_labels:
        name = area["name"]
        collapsible_prefix = next(
            (p for p in PREFIXES_TO_COLLAPSE if name.startswith(f"{p}/")), None)

        if collapsible_prefix:
            lines.add(f"- {collapsible_prefix}/* (multiple specific sub-labels exist)")
        else:
            desc = area["description"]
            lines.add(f"- {name}: {desc}" if desc else f"- {name}")

    return "\n".join(sorted(lines))


def detect_areas(anthropic_key, issue, area_labels):
    """Use Claude to detect which area labels apply to the issue.

    Claude may ignore the format instruction or hallucinate names, so the response
    is validated against the canonical set of area labels.
    """
    log("Detecting areas with Claude")

    taxonomy = format_taxonomy_for_claude(area_labels)
    valid_areas = {label["name"] for label in area_labels}

    system_prompt = """You analyze GitHub issues to identify which area labels apply.

Respond with ONLY a comma-separated list of matching area names. No prose, no explanation,
no markdown, no preamble — just the names.

- Output at most 3 areas, ranked by relevance
- Use exact area names from the taxonomy
- If no areas clearly match, respond with: none
- For languages/*, tooling/*, or parity/*, use the specific sub-label (e.g., "languages/rust",
  tooling/eslint, parity/vscode)

Examples of valid responses (each line is a complete response on its own):
  editor, parity/vim
  ai, ai/agent panel
  none
"""

    user_content = f"""## Area Taxonomy
{taxonomy}

# Issue Title
{issue['title']}

# Issue Body
{issue['body'][:4000]}"""

    response = call_claude(anthropic_key, system_prompt, user_content, max_tokens=100).strip()
    log(f"  Detected areas: {response}")

    if response.lower() == "none":
        return []

    valid, dropped = [], []
    for area in response.split(","):
        area = area.strip()
        (valid if area in valid_areas else dropped).append(area)
    if dropped:
        log(f"  Dropped {len(dropped)} unknown area(s) from Claude response: {dropped}")
    return valid


def parse_duplicate_magnets():
    """Parse known duplicate magnets from tracking issue #46355.

    Returns a list of magnets sorted by duplicate count (most duplicated first).
    Magnets only have number, areas, and dupe_count — use enrich_magnets() to fetch
    title and body_preview for the ones you need.
    """
    log(f"Parsing duplicate magnets from #{TRACKING_ISSUE_NUMBER}")

    issue_data = github_api_get(f"/repos/{REPO_OWNER}/{REPO_NAME}/issues/{TRACKING_ISSUE_NUMBER}")
    body = issue_data.get("body") or ""

    # parse the issue body
    # format: ## area_name
    #         -   [N dupes] https://github.com/zed-industries/zed/issues/NUMBER
    magnets = {}  # number -> {number, areas, dupe_count}
    current_area = None

    for line in body.split("\n"):
        # check for area header
        if line.startswith("## "):
            current_area = line[3:].strip()
            continue

        if not current_area or not line.startswith("-") or "/issues/" not in line:
            continue

        # parse: -   [N dupes] https://github.com/.../issues/NUMBER
        try:
            dupe_count = int(line.split("[")[1].split()[0])
            number = int(line.split("/issues/")[1].split()[0].rstrip(")"))
        except (ValueError, IndexError):
            continue

        # skip "(unlabeled)": these magnets should match everything
        is_unlabeled = current_area == "(unlabeled)"

        if number in magnets:
            if not is_unlabeled:
                magnets[number]["areas"].append(current_area)
        else:
            magnets[number] = {
                "number": number,
                "areas": [] if is_unlabeled else [current_area],
                "dupe_count": dupe_count,
            }

    magnet_list = sorted(magnets.values(), key=lambda m: m["dupe_count"], reverse=True)
    log(f"  Parsed {len(magnet_list)} duplicate magnets")
    return magnet_list


def enrich_magnets(magnets):
    """Fetch title and body_preview for magnets from the API."""
    log(f"  Fetching details for {len(magnets)} magnets")
    for magnet in magnets:
        data = github_api_get(f"/repos/{REPO_OWNER}/{REPO_NAME}/issues/{magnet['number']}")
        magnet["title"] = data["title"]
        magnet["body_preview"] = (data.get("body") or "")[:1000]


def areas_match(detected, magnet_area):
    """Check if detected area matches magnet area. Matches broadly across hierarchy levels."""
    return (
        detected == magnet_area
        or magnet_area.startswith(f"{detected}/")
        or detected.startswith(f"{magnet_area}/")
    )


def filter_magnets_by_areas(magnets, detected_areas):
    """Filter magnets based on detected areas."""
    if not detected_areas:
        return magnets

    detected_set = set(detected_areas)

    def matches(magnet):
        # unlabeled magnets (empty areas) match everything
        if not magnet["areas"]:
            return True
        return any(
            areas_match(detected, magnet_area)
            for detected in detected_set
            for magnet_area in magnet["areas"]
        )

    return list(filter(matches, magnets))


def search_for_similar_issues(issue, detected_areas, max_searches_per_state=6):
    """Search for similar issues — both open and recently closed.

    Runs two passes:
    - Open issues: title keywords / error pattern unrestricted, area searches last 60 days.
    - Closed issues: closed within the last 30 days (across all query types).

    max_searches_per_state caps queries per state to keep token usage and context size bounded.
    """
    log("Searching for similar issues")

    sixty_days_ago = (datetime.now() - timedelta(days=60)).strftime("%Y-%m-%d")
    thirty_days_ago = (datetime.now() - timedelta(days=30)).strftime("%Y-%m-%d")

    title_keywords = [word for word in issue["title"].split() if word.lower() not in STOPWORDS and len(word) > 2]
    keywords_query = " ".join(title_keywords) if title_keywords else None

    # error pattern search: capture 5–90 chars after keyword, colon optional
    error_pattern = r"(?i:\b(?:error|panicked|panic|failed)\b)\s*([^\n]{5,90})"
    error_match = re.search(error_pattern, issue["body"])
    error_snippet = error_match.group(1).strip() if error_match else None

    def build_queries(base, area_window=None):
        queries = []
        if keywords_query:
            queries.append(("title_keywords", f"{base} {keywords_query}"))
        for area in detected_areas:
            area_q = f'{base} label:"area:{area}"'
            if area_window:
                area_q += f" created:>{area_window}"
            queries.append(("area_label", area_q))
        if error_snippet:
            queries.append(("error_pattern", f'{base} in:body "{error_snippet}"'))
        return queries

    open_queries = build_queries(
        f"repo:{REPO_OWNER}/{REPO_NAME} is:issue is:open",
        area_window=sixty_days_ago,
    )
    # closed pass: filter by close date so we catch issues closed recently regardless of
    # when they were opened. closed:> already restricts the result set, so the per-query
    # area window is unnecessary.
    closed_queries = build_queries(
        f"repo:{REPO_OWNER}/{REPO_NAME} is:issue is:closed closed:>{thirty_days_ago}",
    )

    seen_issues = {}
    for state_label, queries in (
        ("open", open_queries[:max_searches_per_state]),
        ("closed", closed_queries[:max_searches_per_state]),
    ):
        for search_type, query in queries:
            log(f"  Search ({state_label} / {search_type}): {query}")
            try:
                results = github_search_issues(query, per_page=15)
                for item in results:
                    number = item["number"]
                    if number != issue["number"] and number not in seen_issues:
                        body = item.get("body") or ""
                        seen_issues[number] = {
                            "number": number,
                            "title": item["title"],
                            "state": item.get("state", ""),
                            "state_reason": item.get("state_reason"),
                            "created_at": item.get("created_at", ""),
                            "body_preview": body[:1000],
                            "source": search_type,
                        }
            except requests.RequestException as e:
                log(f"  Search failed: {e}")

    similar_issues = list(seen_issues.values())
    log(f"  Found {len(similar_issues)} similar issues")
    return similar_issues


def analyze_duplicates(anthropic_key, issue, magnets, search_results):
    """Use Claude to identify duplicates (open) and surface related closed issues.

    Returns (likely_duplicates, possible_duplicates, related_closed_issues).
    """
    top_magnets = magnets[:10]
    magnet_numbers = {m["number"] for m in top_magnets}

    open_results = [r for r in search_results if r["state"] == "open" and r["number"] not in magnet_numbers]
    closed_results = [r for r in search_results if r["state"] == "closed" and r["number"] not in magnet_numbers]

    if not top_magnets and not open_results and not closed_results:
        return [], [], []

    log("Analyzing candidates with Claude")
    enrich_magnets(top_magnets)

    candidates = [
        {"number": m["number"], "title": m["title"], "body_preview": m["body_preview"],
         "state": "open", "state_reason": None, "source": "known_duplicate_magnet"}
        for m in top_magnets
    ] + [
        {"number": r["number"], "title": r["title"], "body_preview": r["body_preview"],
         "state": r["state"], "state_reason": r["state_reason"], "source": "search_result"}
        for r in open_results[:10] + closed_results[:5]
    ]

    system_prompt = """You analyze GitHub issues to (a) identify duplicates among OPEN candidates
and (b) surface recently CLOSED candidates that are useful triage context.

Each candidate has a "state" field ("open" or "closed"), and closed candidates carry a
"state_reason" ("completed", "not_planned", or "duplicate").

# (a) Duplicates — OPEN candidates only

A duplicate means: caused by the SAME BUG in the code, not just similar symptoms.

CRITICAL DISTINCTION — shared symptoms vs shared root cause:
- "models missing", "can't sign in", "editor hangs", "venv not detected" are SYMPTOMS that many
  different bugs can produce. Two reports of the same symptom are NOT duplicates unless you can
  identify a specific shared root cause.
- A duplicate means: if a developer fixed the existing issue, the new issue would also be fixed.
- If the issues just happen to be in the same feature area, or describe similar-sounding problems
  with different specifics (different error messages, different triggers, different platforms,
  different configurations), they are NOT duplicates.

Sort duplicates into two buckets:
- "likely_duplicates": Almost certainly the same bug. You can name a specific shared root cause, and
  the reproduction steps / error messages / triggers are consistent.
- "possible_duplicates": Likely the same bug based on specific technical details, but some
  uncertainty remains.
- Do NOT include issues that merely share symptoms, affect the same feature area, or sound similar
  at a surface level.

Examples of things that are NOT duplicates:
- Two issues about "Copilot models not showing" — one caused by a Zed update breaking the model list,
  the other caused by the user's plan not including those models.
- Two issues about "Zed hangs" — one triggered by network drives, the other by large projects.
- Two issues about "can't sign in" — one caused by a missing system package, the other by a server-side error.

For OPEN duplicates (either bucket), false positives are MUCH worse than false negatives — they
waste the time of both the issue author and the maintainers. When in doubt, omit.

# (b) Related closed issues — CLOSED candidates only

The goal is to give triagers extra context, NOT to claim a duplicate. The bar is lower than for
duplicates: include a closed candidate if a triager would plausibly want to see it when reviewing
the new issue. Examples worth surfacing:
- A recently fixed (state_reason "completed") issue describing the same symptom — triager may ask
  the reporter to retest on the latest build.
- A cluster of similar issues closed as "not_planned" — signals a known limitation or design choice.
- A previously triaged duplicate (state_reason "duplicate") in the same code area.

Include at most 5 closed candidates, prioritized by relevance.

# Output format

Output only valid JSON (no markdown code blocks):
{
  "likely_duplicates": [
    {
      "number": 12345,
      "shared_root_cause": "The specific bug/root cause shared by both issues",
      "explanation": "Brief explanation with concrete evidence from both issues"
    }
  ],
  "possible_duplicates": [
    {
      "number": 12345,
      "shared_root_cause": "The specific bug/root cause shared by both issues",
      "explanation": "Brief explanation with concrete evidence from both issues"
    }
  ],
  "related_closed_issues": [
    {
      "number": 12345,
      "explanation": "Brief explanation of why this is useful triage context"
    }
  ]
}

Return empty arrays where nothing relevant is found."""

    user_content = f"""## New Issue #{issue['number']}
**Title:** {issue['title']}

**Body:**
{issue['body'][:3000]}

## Existing Issues to Compare
{json.dumps(candidates, indent=2)}"""

    response = call_claude(anthropic_key, system_prompt, user_content, max_tokens=2048)

    # Claude sometimes wraps JSON in a ```json ... ``` fence despite the prompt forbidding it
    fence = re.match(r"^\s*```(?:json)?\s*\n?(.*?)\n?```\s*$", response, re.DOTALL)
    if fence:
        response = fence.group(1)

    try:
        data = json.loads(response)
    except json.JSONDecodeError as e:
        log(f"  Failed to parse Claude response as JSON: {e}")
        log(f"  Raw response:\n{response}")
        sys.exit(1)

    likely = data.get("likely_duplicates", [])
    possible = data.get("possible_duplicates", [])
    closed = data.get("related_closed_issues", [])
    log(f"  Found {len(likely) + len(possible) + len(closed)} potential matches")
    return likely, possible, closed


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Identify potential duplicate issues")
    parser.add_argument("issue_number", type=int, help="Issue number to analyze")
    parser.add_argument("--dry-run", action="store_true", help="Skip posting comment, just log what would be posted")
    args = parser.parse_args()

    github_token = os.environ.get("GITHUB_TOKEN")
    anthropic_key = os.environ.get("ANTHROPIC_API_KEY")

    if not github_token:
        log("Error: GITHUB_TOKEN not set")
        sys.exit(1)
    if not anthropic_key:
        log("Error: ANTHROPIC_API_KEY not set")
        sys.exit(1)

    GITHUB_HEADERS = {
        "Authorization": f"Bearer {github_token}",
        "Accept": "application/vnd.github+json",
        "X-GitHub-Api-Version": "2022-11-28",
    }

    issue = fetch_issue(args.issue_number)
    if should_skip(issue):
        print(json.dumps({"skipped": True}))
        sys.exit(0)

    # detect areas
    detected_areas = detect_areas(anthropic_key, issue, fetch_area_labels())

    # search for potential duplicates and related closed issues
    all_magnets = parse_duplicate_magnets()
    relevant_magnets = filter_magnets_by_areas(all_magnets, detected_areas)
    search_results = search_for_similar_issues(issue, detected_areas)

    # analyze candidates
    likely_duplicates, possible_duplicates, related_closed_issues = analyze_duplicates(
        anthropic_key, issue, relevant_magnets, search_results
    )

    # resolve close reason from our search results (the source of truth) so we don't depend
    # on Claude to faithfully echo it back
    results_by_number = {r["number"]: r for r in search_results}
    for m in related_closed_issues:
        m["state_reason"] = results_by_number[m["number"]]["state_reason"]

    comment_body = build_comment(likely_duplicates, possible_duplicates, related_closed_issues)
    commented = False

    if comment_body:
        if args.dry_run:
            log("Dry run - would post comment:\n" + "-" * 40 + "\n" + comment_body + "\n" + "-" * 40)
        else:
            log("Posting comment")
            try:
                post_comment(issue["number"], comment_body)
                commented = True
            except requests.RequestException as e:
                log(f"  Failed to post comment: {e}")
                log(f"  Comment we were trying to post:\n{comment_body}")
                sys.exit(1)

    print(json.dumps({
        "skipped": False,
        "issue": {
            "number": issue["number"],
            "title": issue["title"],
            "author": issue["author"],
            "type": issue["type"],
        },
        "detected_areas": detected_areas,
        "magnets_count": len(relevant_magnets),
        "search_results_count": len(search_results),
        "likely_duplicates": likely_duplicates,
        "possible_duplicates": possible_duplicates,
        "related_closed_issues": related_closed_issues,
        "commented": commented,
    }))