#!/usr/bin/env python3
"""
GitHub API utilities for scraping and metadata collection.
Separated from scrape_gh_docs.py to keep the main script slimmer.
"""

from __future__ import annotations

import os
import time
import logging
import threading
from urllib.parse import quote_plus
from typing import Optional, Dict, Any, List
import json

import requests
import aiohttp

GITHUB_API = "https://api.github.com"

# Use the same logger name as the main script so logs route through its handler
logger = logging.getLogger("scrape_gh_docs")

_thread_local = threading.local()


def github_headers() -> Dict[str, str]:
    token = os.getenv("GITHUB_TOKEN")
    assert token is not None, "Set the Github token to run this script!"
    h = {"Accept": "application/vnd.github.v3+json", "User-Agent": "docs-scraper/1.0"}
    if token:
        h["Authorization"] = f"token {token}"
    return h


def get_session() -> requests.Session:
    sess = getattr(_thread_local, "session", None)
    if sess is None:
        sess = requests.Session()
        _thread_local.session = sess
    return sess


def request_json(
    url: str, params: Optional[dict] = None, accept_status=(200,), max_retries: int = 3
):
    for attempt in range(max_retries):
        resp = get_session().get(
            url, headers=github_headers(), params=params, timeout=30
        )
        if resp.status_code in accept_status:
            # Some endpoints return empty responses on success (e.g. 204). Handle json errors defensively.
            try:
                return resp.json()
            except Exception:
                return None
        if resp.status_code in (403, 529):
            # rate limit or blocked - try to get reset and sleep
            reset = resp.headers.get("X-RateLimit-Reset")
            ra = resp.headers.get("Retry-After")
            if ra:
                wait = int(ra)
            elif reset:
                wait = max(5, int(reset) - int(time.time()))
            else:
                wait = 30
            logger.warning(
                f"{resp.status_code} from {url}. Sleeping {wait}s (attempt {attempt + 1}/{max_retries})"
            )
            time.sleep(wait)
            continue
        if 500 <= resp.status_code < 600:
            backoff = (attempt + 1) * 5
            logger.warning(f"{resp.status_code} from {url}. Backing off {backoff}s")
            time.sleep(backoff)
            continue
        logger.error(f"Request to {url} returned {resp.status_code}: {resp.text}")
        return None
    logger.error(f"Exhausted retries for {url}")
    return None


def find_readme_file(
    owner: str, repo: str, ref: Optional[str] = None
) -> Optional[Dict[str, str]]:
    """
    Find a README file located at the repository root using the Contents API.

    Returns a dict with keys: 'name', 'path', 'download_url' if found, else None.
    README detection is case-insensitive and prioritizes extensions: .md < .rst < .org < others,
    and shorter names if tie-break is needed.
    """
    # List root contents; passing empty path lists the repository root
    root_list = get_contents(owner, repo, "", ref=ref)
    if not isinstance(root_list, list):
        return None
    candidates: List[tuple[tuple[int, int], Dict[str, Any]]] = []
    prio_map = {".md": 0, ".rst": 1, ".org": 2}
    for it in root_list:
        try:
            if it.get("type") != "file":
                continue
            name = it.get("name") or ""
            if not name:
                continue
            if not name.lower().startswith("readme"):
                continue
            ext = ""
            if "." in name:
                ext = name[name.rfind(".") :].lower()
            prio = (prio_map.get(ext, 3), len(name))
            candidates.append((prio, it))
        except Exception:
            continue
    if not candidates:
        return None
    candidates.sort(key=lambda x: x[0])
    best = candidates[0][1]
    # The contents API entry includes 'name', 'path', 'download_url'
    name = best.get("name")
    path = best.get("path")
    download_url = best.get("download_url")
    if (
        isinstance(name, str)
        and isinstance(path, str)
        and isinstance(download_url, str)
    ):
        return {"name": name, "path": path, "download_url": download_url}
    return None


def download_readme_to(
    owner: str, repo: str, dest_root, ref: Optional[str] = None
) -> Optional[Dict[str, str]]:
    """
    Locate README at repo root and download it into dest_root/NAME.
    Returns the README info dict if downloaded, else None.
    """
    info = find_readme_file(owner, repo, ref=ref)
    if not info:
        return None
    dest_root.mkdir(parents=True, exist_ok=True)
    dest = dest_root / info["name"]
    try:
        download_file(info["download_url"], dest)
        return info
    except Exception:
        logger.warning(f"Failed to download README for {owner}/{repo}: {info['name']}")
        return None


def download_file(url: str, dest_path):
    dest_path.parent.mkdir(parents=True, exist_ok=True)
    with get_session().get(url, headers=github_headers(), stream=True, timeout=60) as r:
        r.raise_for_status()
        with open(dest_path, "wb") as f:
            for chunk in r.iter_content(chunk_size=8192):
                if chunk:
                    f.write(chunk)


# === High-level GitHub API helpers ===


def get_repo_info(owner: str, repo: str) -> Optional[Dict[str, Any]]:
    url = f"{GITHUB_API}/repos/{owner}/{repo}"
    return request_json(url)


def get_default_branch(
    owner: str, repo: str, repo_json: Optional[Dict[str, Any]] = None
) -> Optional[str]:
    if repo_json and "default_branch" in repo_json:
        return repo_json["default_branch"]
    info = get_repo_info(owner, repo)
    if not info:
        return None
    return info.get("default_branch")


def get_latest_commit_date(
    owner: str,
    repo: str,
    ref: Optional[str],
    repo_json: Optional[Dict[str, Any]] = None,
) -> Optional[str]:
    """
    Return ISO8601 date string of the latest commit on the given ref (branch or SHA).
    Falls back to repo's pushed_at if commits endpoint returns nothing.
    """
    branch = ref or (repo_json.get("default_branch") if repo_json else None) or "main"
    commits = request_json(
        f"{GITHUB_API}/repos/{owner}/{repo}/commits",
        params={"sha": branch, "per_page": 1},
        accept_status=(200,),
    )
    if isinstance(commits, list) and commits:
        try:
            return commits[0]["commit"]["author"]["date"]
        except Exception:
            pass
    if repo_json is None:
        repo_json = get_repo_info(owner, repo) or {}
    return repo_json.get("pushed_at")


def get_contents(owner: str, repo: str, path: str, ref: Optional[str] = None):
    url = f"{GITHUB_API}/repos/{owner}/{repo}/contents/{quote_plus(path)}"
    params = {"ref": ref} if ref else None
    return request_json(url, params=params, accept_status=(200, 404))


def get_owner_type(owner: str) -> Optional[str]:
    info = request_json(f"{GITHUB_API}/users/{owner}", accept_status=(200, 404))
    if not info:
        return None
    return info.get("type")


def get_org_repos(owner: str, per_page: int = 100) -> List[Dict[str, Any]]:
    owner_type = get_owner_type(owner)
    base = "orgs" if owner_type == "Organization" else "users"
    repos: List[Dict[str, Any]] = []
    page = 1
    while True:
        url = f"{GITHUB_API}/{base}/{owner}/repos"
        params = {"per_page": per_page, "page": page}
        data = request_json(url, params=params)
        if not data:
            if page == 1 and base == "orgs":
                base = "users"
                continue
            break
        repos.extend(data)
        if len(data) < per_page:
            break
        page += 1
    return repos


def search_repos(query: str, per_page: int = 5) -> List[Dict[str, Any]]:
    url = f"{GITHUB_API}/search/repositories"
    params = {"q": query, "per_page": per_page}
    res = request_json(url, params=params, accept_status=(200,))
    if not res:
        return []
    return res.get("items", [])


def get_repo_tree_paths(owner: str, repo: str, ref: Optional[str]) -> List[str]:
    ref = ref or "main"
    url = f"{GITHUB_API}/repos/{owner}/{repo}/git/trees/{quote_plus(ref)}"
    params = {"recursive": 1}
    data = request_json(url, params=params, accept_status=(200,))
    if not data or "tree" not in data:
        return []
    paths: List[str] = []
    for entry in data["tree"]:
        if entry.get("type") == "blob" and "path" in entry:
            paths.append(entry["path"])
    return paths


def get_repo_tree_md_paths(owner: str, repo: str, ref: Optional[str]) -> List[str]:
    """
    Return only Markdown file paths from the repository tree on the given ref
    using the Git Trees API (recursive=1).

    This is a convenience wrapper over get_repo_tree_paths() that filters to
    .md files, case-insensitive.
    """
    all_paths = get_repo_tree_paths(owner, repo, ref)
    return [p for p in all_paths if p.lower().endswith(".md")]


async def fetch_repo_readme_markdown(
    session: aiohttp.ClientSession, owner: str, repo: str
) -> Optional[str]:
    """
    Fetch README markdown using the contents API, trying README.md and readme.md.
    Returns the markdown text or None if not found.
    """
    headers = github_headers()
    for name in ("README.md", "readme.md"):
        url = f"{GITHUB_API}/repos/{owner}/{repo}/contents/{name}"
        try:
            async with session.get(url, headers=headers) as resp:
                if resp.status == 200:
                    data = await resp.json()
                    if isinstance(data, dict) and "download_url" in data:
                        download_url = data["download_url"]
                        async with session.get(download_url, headers=headers) as d:
                            if d.status == 200:
                                return await d.text()
        except Exception:
            continue
    # Fallback: list the repo tree at depth=0 (root only) and select any file starting with README*
    try:
        # Get default branch to address the tree head
        repo_url = f"{GITHUB_API}/repos/{owner}/{repo}"
        default_branch = "main"
        async with session.get(repo_url, headers=headers) as rinfo:
            if rinfo.status == 200:
                info = await rinfo.json()
                if isinstance(info, dict) and info.get("default_branch"):
                    default_branch = info["default_branch"]

        # Depth=0 tree (root only). Omitting recursive parameter implies non-recursive.
        tree_url = (
            f"{GITHUB_API}/repos/{owner}/{repo}/git/trees/{quote_plus(default_branch)}"
        )
        async with session.get(tree_url, headers=headers) as rtree:
            if rtree.status != 200:
                return None
            tree = await rtree.json()
            if not isinstance(tree, dict) or "tree" not in tree:
                return None

            entries = tree["tree"]
            # Find candidates that start with README (case-insensitive) and are files (blobs)
            candidates = []
            for e in entries:
                if e.get("type") != "blob":
                    continue
                path = e.get("path")
                if not path:
                    continue
                name_lower = path.lower()
                if name_lower.startswith("readme"):
                    # Priority: .md < .rst < .org < others; shorter names first
                    prio_map = {".md": 0, ".rst": 1, ".org": 2}
                    ext = ""
                    if "." in path:
                        ext = path[path.rfind(".") :].lower()
                    prio = (prio_map.get(ext, 3), len(path))
                    candidates.append((prio, path))

            if not candidates:
                return None
            candidates.sort()
            chosen_path = candidates[0][1]

            # Fetch the chosen README variant via contents API to get a direct download URL
            contents_url = (
                f"{GITHUB_API}/repos/{owner}/{repo}/contents/{quote_plus(chosen_path)}"
            )
            async with session.get(contents_url, headers=headers) as rc:
                if rc.status != 200:
                    return None
                cdata = await rc.json()
                if isinstance(cdata, dict) and "download_url" in cdata:
                    download_url = cdata["download_url"]
                    async with session.get(download_url, headers=headers) as rd:
                        if rd.status == 200:
                            return await rd.text()
    except Exception:
        return None

    return None


async def fetch_repo_description(
    session: aiohttp.ClientSession, owner: str, repo: str
) -> Optional[str]:
    url = f"https://api.github.com/repos/{owner}/{repo}"
    try:
        async with session.get(url, headers=github_headers()) as resp:
            if resp.status == 200:
                data = await resp.json()
                if isinstance(data, dict) and "description" in data:
                    desc = data["description"]
                    if isinstance(desc, str):
                        return desc
    except Exception:
        return None
    return None


# === GitHub GraphQL helpers ===

GITHUB_GRAPHQL = "https://api.github.com/graphql"


def _graphql_headers() -> Dict[str, str]:
    token = os.getenv("GITHUB_TOKEN")
    h = {"Content-Type": "application/json", "User-Agent": "docs-scraper/1.0"}
    if token:
        # GitHub GraphQL expects a bearer token
        h["Authorization"] = f"bearer {token}"
    return h


def fetch_repos_metadata_graphql(
    pairs: List[tuple[str, str]],
    topics_limit: int = 20,
) -> Dict[str, Dict[str, Any]]:
    """
    Batch-fetch repository metadata via GitHub GraphQL for a list of (owner, repo) pairs.

    Returns a mapping from "owner/repo" -> {
        "name": str | None,
        "description": str | None,
        "stars": int | None,
        "default_branch": str | None,
        "last_commit_date": str | None,
        "language": str | None,
        "topics": List[str],
        "is_fork": bool | None,
        "parent_url": str | None,
    }

    Notes:
    - last_commit_date is taken from the latest commit on the default branch when available;
      falls back to pushedAt otherwise.
    - Callers should keep batch sizes modest (e.g., <= 30) to stay under GraphQL cost limits.
    """
    if not pairs:
        return {}
    # Build a single query with aliased repository fields and use variables for owner/name
    # Example:
    # query($owner0: String!, $name0: String!, ...) {
    #   repo_0: repository(owner: $owner0, name: $name0) { ...fields }
    # }
    vars: Dict[str, Any] = {}
    fields: List[str] = []
    for i, (owner, name) in enumerate(pairs):
        vars[f"owner{i}"] = owner
        vars[f"name{i}"] = name
        alias = f"repo_{i}"
        header = f"{alias}: repository(owner: $owner{i}, name: $name{i}) "
        topics_fragment = (
            "  repositoryTopics(first: "
            + str(topics_limit)
            + ") { nodes { topic { name } } }\n"
            if topics_limit and topics_limit > 0
            else ""
        )
        body = (
            "{\n"
            "  name\n"
            "  description\n"
            "  stargazerCount\n"
            "  pushedAt\n"
            "  isFork\n"
            "  parent { url nameWithOwner }\n"
            "  primaryLanguage { name }\n" + topics_fragment + "  defaultBranchRef {\n"
            "    name\n"
            "    target {\n"
            "      ... on Commit {\n"
            "        history(first: 1) {\n"
            "          nodes {\n"
            "            committedDate\n"
            "          }\n"
            "        }\n"
            "      }\n"
            "    }\n"
            "  }\n"
            "}\n"
        )
        fields.append(header + body)
    # Assemble query
    var_decls = " ".join(
        [f"$owner{i}: String!, $name{i}: String!" for i in range(len(pairs))]
    )
    query = "query(" + var_decls + ") {\n" + "\n".join(fields) + "\n}"

    payload = {"query": query, "variables": vars}
    max_retries = 3
    for attempt in range(max_retries):
        resp = get_session().post(
            GITHUB_GRAPHQL,
            headers=_graphql_headers(),
            data=json.dumps(payload),
            timeout=60,
        )
        if resp.status_code == 200:
            try:
                data = resp.json()
            except Exception:
                logger.error("Failed to decode GraphQL JSON response")
                return {}
            if "errors" in data and data["errors"]:
                # Log the first error for context but still try to parse any partial data
                logger.warning(f"GraphQL response has errors: {data['errors'][0]}")
            repos = data.get("data", {}) or {}
            break
        if resp.status_code in (403, 529):
            reset = resp.headers.get("X-RateLimit-Reset")
            ra = resp.headers.get("Retry-After")
            if ra:
                wait = int(ra)
            elif reset:
                wait = max(5, int(reset) - int(time.time()))
            else:
                wait = 30
            logger.warning(
                f"GraphQL {resp.status_code}. Sleeping {wait}s (attempt {attempt + 1}/{max_retries})"
            )
            time.sleep(wait)
            continue
        if 500 <= resp.status_code < 600:
            backoff = (attempt + 1) * 5
            logger.warning(f"GraphQL {resp.status_code}. Backing off {backoff}s")
            time.sleep(backoff)
            continue
        logger.error(f"GraphQL error {resp.status_code}: {resp.text}")
        return {}
    else:
        logger.error("Exhausted retries for GraphQL request")
        return {}

    out: Dict[str, Dict[str, Any]] = {}
    for i, (owner, name) in enumerate(pairs):
        alias = f"repo_{i}"
        r = repos.get(alias)
        key = f"{owner}/{name}"
        if not isinstance(r, dict):
            out[key] = {
                "name": None,
                "description": None,
                "stars": None,
                "default_branch": None,
                "last_commit_date": None,
                "language": None,
                "topics": [],
                "is_fork": None,
                "parent_url": None,
            }
            continue
        repo_name = r.get("name")
        desc = r.get("description")
        stars = r.get("stargazerCount")
        pushed_at = r.get("pushedAt")
        is_fork = r.get("isFork")
        parent = r.get("parent") or {}
        parent_url = parent.get("url") if isinstance(parent, dict) else None
        lang_obj = r.get("primaryLanguage") or {}
        language = lang_obj.get("name") if isinstance(lang_obj, dict) else None
        topics_list: List[str] = []
        rt = r.get("repositoryTopics") or {}
        nodes = rt.get("nodes") if isinstance(rt, dict) else None
        if isinstance(nodes, list):
            for node in nodes:
                t = None
                if isinstance(node, dict):
                    topic = node.get("topic")
                    if isinstance(topic, dict):
                        t = topic.get("name")
                if isinstance(t, str):
                    topics_list.append(t)
        dbr = r.get("defaultBranchRef") or {}
        default_branch = dbr.get("name") if isinstance(dbr, dict) else None
        last_commit_date = pushed_at
        if isinstance(dbr, dict):
            tgt = dbr.get("target") or {}
            hist = tgt.get("history") or {}
            nodes = hist.get("nodes") or []
            if isinstance(nodes, list) and nodes:
                lcd = nodes[0].get("committedDate")
                if isinstance(lcd, str):
                    last_commit_date = lcd
        out[key] = {
            "name": repo_name if isinstance(repo_name, str) else None,
            "description": desc if isinstance(desc, str) else None,
            "stars": stars,
            "default_branch": default_branch,
            "last_commit_date": last_commit_date,
            "language": language if isinstance(language, str) else None,
            "topics": topics_list,
            "is_fork": is_fork if isinstance(is_fork, bool) else None,
            "parent_url": parent_url if isinstance(parent_url, str) else None,
        }
    return out