"""Git history narrator — turns raw commits into editorial prose."""
import os
import re
import requests
from app.core.ai import call_ai_json

_GITHUB_API = "https://api.github.com"
_SYSTEM = """You are a senior engineering writer and technical storyteller.
You transform dry git commit logs into compelling, editorial-quality engineering narratives.
Write like a thoughtful tech lead preparing a sprint retrospective for the whole company.
Be specific about what was built, avoid jargon where plain language works, and surface the human story behind the code.
Return ONLY valid JSON — no markdown fences."""

_PROMPT_TMPL = """Narrate the following git history into an editorial engineering report.

GIT HISTORY:
---
{log}
---

Return a JSON object with EXACTLY these keys:
{{
  "period_label": "<inferred time period, e.g. 'Sprint 42' or 'Week of Jan 15, 2025'>",
  "highlights": [
    {{
      "title": "<punchy title for the biggest story>",
      "narrative": "<2-3 paragraph editorial story — what changed, why it matters, what comes next>",
      "key_commit": "<most important commit message verbatim>",
      "impact": "<one sentence business impact>"
    }}
  ],
  "tech_debt": [
    {{
      "icon": "<material symbol name, e.g. cleaning_services|speed|bug_report|tune>",
      "title": "<short title>",
      "description": "<2-3 sentences on what was fixed/refactored and the measurable benefit>"
    }}
  ],
  "milestones": [
    {{
      "status": "<shipped|in_progress|planned>",
      "title": "<milestone name>",
      "narrative": "<editorial paragraph on this milestone>",
      "contributors": ["<name or handle>"]
    }}
  ],
  "commits": [
    {{
      "hash": "<7-char hash or empty string>",
      "message": "<commit message>",
      "author": "<author name or handle>",
      "time": "<relative time e.g. '2 hours ago'>",
      "type": "<feat|fix|docs|refactor|chore|test|perf>"
    }}
  ],
  "summary_stats": {{
    "total_commits": <integer>,
    "contributors": <integer>,
    "features": <integer>,
    "fixes": <integer>
  }}
}}

Aim for 2-3 highlights, 2-3 tech_debt items, 2-3 milestones.
If the log is sparse, extrapolate intelligently from what's there.
commits should list ALL commits from the log (max 20)."""


def _fetch_github_commits(owner: str, repo: str, limit: int = 30) -> str:
    """Fetch recent commits from GitHub and format as git log text."""
    token = os.environ.get("GITHUB_TOKEN", "")
    headers = {"Accept": "application/vnd.github.v3+json"}
    if token:
        headers["Authorization"] = f"Bearer {token}"
    r = requests.get(f"{_GITHUB_API}/repos/{owner}/{repo}/commits?per_page={limit}",
                     headers=headers, timeout=20)
    r.raise_for_status()
    lines = []
    for c in r.json():
        sha   = c["sha"][:7]
        msg   = c["commit"]["message"].split("\n")[0]
        name  = c["commit"]["author"]["name"]
        date  = c["commit"]["author"]["date"]
        lines.append(f"commit {sha}\nAuthor: {name}\nDate:   {date}\n\n    {msg}\n")
    return "\n".join(lines)


def _parse_github_url(text: str):
    """Return (owner, repo) if text looks like a GitHub URL, else None."""
    m = re.search(r"github\.com/([^/\s]+)/([^/\s]+?)(?:\.git)?(?:\s|$)", text)
    if m:
        return m.group(1), m.group(2)
    parts = text.strip().split("/")
    if len(parts) == 2 and " " not in text:
        return parts[0], parts[1]
    return None


def narrate(raw_input: str) -> dict:
    """Narrate a git history. raw_input can be a GitHub URL or raw git log text."""
    parsed = _parse_github_url(raw_input.strip())
    if parsed:
        try:
            owner, repo = parsed
            log = _fetch_github_commits(owner, repo)
        except Exception as e:
            log = raw_input  # fallback to treating as raw log
    else:
        log = raw_input

    prompt = _PROMPT_TMPL.format(log=log[:8000])
    return call_ai_json([{"role": "user", "content": prompt}], system=_SYSTEM) or {}