#!/usr/bin/env python3
"""
PR Complexity Scorer - Estimate review effort for PRs.
"""

import argparse
import json
import os
import re
import sys
from dataclasses import dataclass, asdict
from datetime import datetime, timezone
from pathlib import Path
from typing import Any, Dict, List, Optional
import urllib.request
import urllib.error

GITEA_BASE = "https://forge.alexanderwhitestone.com/api/v1"

DEPENDENCY_FILES = {
    "requirements.txt", "pyproject.toml", "setup.py", "setup.cfg",
    "Pipfile", "poetry.lock", "package.json", "yarn.lock", "Gemfile",
    "go.mod", "Cargo.toml", "pom.xml", "build.gradle"
}

TEST_PATTERNS = [
    r"tests?/.*\.py$", r".*_test\.py$", r"test_.*\.py$",
    r"spec/.*\.rb$", r".*_spec\.rb$",
    r"__tests__/", r".*\.test\.(js|ts|jsx|tsx)$"
]

WEIGHT_FILES = 0.25
WEIGHT_LINES = 0.25
WEIGHT_DEPS = 0.30
WEIGHT_TEST_COV = 0.20

SMALL_FILES = 5
MEDIUM_FILES = 20
LARGE_FILES = 50

SMALL_LINES = 100
MEDIUM_LINES = 500
LARGE_LINES = 2000

TIME_PER_POINT = {1: 5, 2: 10, 3: 15, 4: 20, 5: 25, 6: 30, 7: 45, 8: 60, 9: 90, 10: 120}


@dataclass
class PRComplexity:
    pr_number: int
    title: str
    files_changed: int
    additions: int
    deletions: int
    has_dependency_changes: bool
    test_coverage_delta: Optional[int]
    score: int
    estimated_minutes: int
    reasons: List[str]

    def to_dict(self) -> dict:
        return asdict(self)


class GiteaClient:
    def __init__(self, token: str):
        self.token = token
        self.base_url = GITEA_BASE.rstrip("/")

    def _request(self, path: str, params: Dict = None) -> Any:
        url = f"{self.base_url}{path}"
        if params:
            qs = "&".join(f"{k}={v}" for k, v in params.items() if v is not None)
            url += f"?{qs}"

        req = urllib.request.Request(url)
        req.add_header("Authorization", f"token {self.token}")
        req.add_header("Content-Type", "application/json")

        try:
            with urllib.request.urlopen(req, timeout=30) as resp:
                return json.loads(resp.read().decode())
        except urllib.error.HTTPError as e:
            print(f"API error {e.code}: {e.read().decode()[:200]}", file=sys.stderr)
            return None
        except urllib.error.URLError as e:
            print(f"Network error: {e}", file=sys.stderr)
            return None

    def get_open_prs(self, org: str, repo: str) -> List[Dict]:
        prs = []
        page = 1
        while True:
            batch = self._request(f"/repos/{org}/{repo}/pulls", {"limit": 50, "page": page, "state": "open"})
            if not batch:
                break
            prs.extend(batch)
            if len(batch) < 50:
                break
            page += 1
        return prs

    def get_pr_files(self, org: str, repo: str, pr_number: int) -> List[Dict]:
        files = []
        page = 1
        while True:
            batch = self._request(
                f"/repos/{org}/{repo}/pulls/{pr_number}/files",
                {"limit": 100, "page": page}
            )
            if not batch:
                break
            files.extend(batch)
            if len(batch) < 100:
                break
            page += 1
        return files

    def post_comment(self, org: str, repo: str, pr_number: int, body: str) -> bool:
        data = json.dumps({"body": body}).encode("utf-8")
        req = urllib.request.Request(
            f"{self.base_url}/repos/{org}/{repo}/issues/{pr_number}/comments",
            data=data,
            method="POST",
            headers={"Authorization": f"token {self.token}", "Content-Type": "application/json"}
        )
        try:
            with urllib.request.urlopen(req, timeout=30) as resp:
                return resp.status in (200, 201)
        except urllib.error.HTTPError:
            return False


def is_dependency_file(filename: str) -> bool:
    return any(filename.endswith(dep) for dep in DEPENDENCY_FILES)


def is_test_file(filename: str) -> bool:
    return any(re.search(pattern, filename) for pattern in TEST_PATTERNS)


def score_pr(
    files_changed: int,
    additions: int,
    deletions: int,
    has_dependency_changes: bool,
    test_coverage_delta: Optional[int] = None
) -> tuple[int, int, List[str]]:
    score = 1.0
    reasons = []

    # Files changed
    if files_changed <= SMALL_FILES:
        fscore = 1.0
        reasons.append("small number of files changed")
    elif files_changed <= MEDIUM_FILES:
        fscore = 2.0
        reasons.append("moderate number of files changed")
    elif files_changed <= LARGE_FILES:
        fscore = 2.5
        reasons.append("large number of files changed")
    else:
        fscore = 3.0
        reasons.append("very large PR spanning many files")

    # Lines changed
    total_lines = additions + deletions
    if total_lines <= SMALL_LINES:
        lscore = 1.0
        reasons.append("small change size")
    elif total_lines <= MEDIUM_LINES:
        lscore = 2.0
        reasons.append("moderate change size")
    elif total_lines <= LARGE_LINES:
        lscore = 3.0
        reasons.append("large change size")
    else:
        lscore = 4.0
        reasons.append("very large change")

    # Dependency changes
    if has_dependency_changes:
        dscore = 2.5
        reasons.append("dependency changes (architectural impact)")
    else:
        dscore = 0.0

    # Test coverage delta
    tscore = 0.0
    if test_coverage_delta is not None:
        if test_coverage_delta > 0:
            reasons.append(f"test additions (+{test_coverage_delta} test files)")
            tscore = -min(2.0, test_coverage_delta / 2.0)
        elif test_coverage_delta < 0:
            reasons.append(f"test removals ({abs(test_coverage_delta)} test files)")
            tscore = min(2.0, abs(test_coverage_delta) * 0.5)
    else:
        reasons.append("test coverage change not assessed")

    # Weighted sum, scaled by 3 to use full 1-10 range
    bonus = (fscore * WEIGHT_FILES) + (lscore * WEIGHT_LINES) + (dscore * WEIGHT_DEPS) + (tscore * WEIGHT_TEST_COV)
    scaled_bonus = bonus * 3.0
    score = 1.0 + scaled_bonus

    final_score = max(1, min(10, int(round(score))))
    est_minutes = TIME_PER_POINT.get(final_score, 30)

    return final_score, est_minutes, reasons


def analyze_pr(client: GiteaClient, org: str, repo: str, pr_data: Dict) -> PRComplexity:
    pr_num = pr_data["number"]
    title = pr_data.get("title", "")
    files = client.get_pr_files(org, repo, pr_num)

    additions = sum(f.get("additions", 0) for f in files)
    deletions = sum(f.get("deletions", 0) for f in files)
    filenames = [f.get("filename", "") for f in files]

    has_deps = any(is_dependency_file(f) for f in filenames)

    test_added = sum(1 for f in files if f.get("status") == "added" and is_test_file(f.get("filename", "")))
    test_removed = sum(1 for f in files if f.get("status") == "removed" and is_test_file(f.get("filename", "")))
    test_delta = test_added - test_removed if (test_added or test_removed) else None

    score, est_min, reasons = score_pr(
        files_changed=len(files),
        additions=additions,
        deletions=deletions,
        has_dependency_changes=has_deps,
        test_coverage_delta=test_delta
    )

    return PRComplexity(
        pr_number=pr_num,
        title=title,
        files_changed=len(files),
        additions=additions,
        deletions=deletions,
        has_dependency_changes=has_deps,
        test_coverage_delta=test_delta,
        score=score,
        estimated_minutes=est_min,
        reasons=reasons
    )


def build_comment(complexity: PRComplexity) -> str:
    change_desc = f"{complexity.files_changed} files, +{complexity.additions}/-{complexity.deletions} lines"
    deps_note = "\n- :warning: Dependency changes detected — architectural review recommended" if complexity.has_dependency_changes else ""
    test_note = ""
    if complexity.test_coverage_delta is not None:
        if complexity.test_coverage_delta > 0:
            test_note = f"\n- :+1: {complexity.test_coverage_delta} test file(s) added"
        elif complexity.test_coverage_delta < 0:
            test_note = f"\n- :warning: {abs(complexity.test_coverage_delta)} test file(s) removed"

    comment = f"## 📊 PR Complexity Analysis\n\n"
    comment += f"**PR #{complexity.pr_number}: {complexity.title}**\n\n"
    comment += f"| Metric | Value |\n|--------|-------|\n"
    comment += f"| Changes | {change_desc} |\n"
    comment += f"| Complexity Score | **{complexity.score}/10** |\n"
    comment += f"| Estimated Review Time | ~{complexity.estimated_minutes} minutes |\n\n"
    comment += f"### Scoring rationale:"
    for r in complexity.reasons:
        comment += f"\n- {r}"
    if deps_note:
        comment += deps_note
    if test_note:
        comment += test_note
    comment += f"\n\n---\n"
    comment += f"*Generated by PR Complexity Scorer — [issue #135](https://forge.alexanderwhitestone.com/Timmy_Foundation/compounding-intelligence/issues/135)*"
    return comment


def main():
    parser = argparse.ArgumentParser(description="PR Complexity Scorer")
    parser.add_argument("--org", default="Timmy_Foundation")
    parser.add_argument("--repo", default="compounding-intelligence")
    parser.add_argument("--token", default=os.environ.get("GITEA_TOKEN") or os.path.expanduser("~/.config/gitea/token"))
    parser.add_argument("--dry-run", action="store_true")
    parser.add_argument("--apply", action="store_true")
    parser.add_argument("--output", default="metrics/pr_complexity.json")
    args = parser.parse_args()

    token_path = args.token
    if os.path.exists(token_path):
        with open(token_path) as f:
            token = f.read().strip()
    else:
        token = args.token

    if not token:
        print("ERROR: No Gitea token provided", file=sys.stderr)
        sys.exit(1)

    client = GiteaClient(token)

    print(f"Fetching open PRs for {args.org}/{args.repo}...")
    prs = client.get_open_prs(args.org, args.repo)
    if not prs:
        print("No open PRs found.")
        sys.exit(0)

    print(f"Found {len(prs)} open PR(s). Analyzing...")

    results = []
    Path(args.output).parent.mkdir(parents=True, exist_ok=True)

    for pr in prs:
        pr_num = pr["number"]
        title = pr.get("title", "")
        print(f"  Analyzing PR #{pr_num}: {title[:60]}")

        try:
            complexity = analyze_pr(client, args.org, args.repo, pr)
            results.append(complexity.to_dict())

            comment = build_comment(complexity)

            if args.dry_run:
                print(f"    → Score: {complexity.score}/10, Est: {complexity.estimated_minutes}min [DRY-RUN]")
            elif args.apply:
                success = client.post_comment(args.org, args.repo, pr_num, comment)
                status = "[commented]" if success else "[FAILED]"
                print(f"    → Score: {complexity.score}/10, Est: {complexity.estimated_minutes}min {status}")
            else:
                print(f"    → Score: {complexity.score}/10, Est: {complexity.estimated_minutes}min [no action]")

        except Exception as e:
            print(f"    ERROR analyzing PR #{pr_num}: {e}", file=sys.stderr)

    with open(args.output, "w") as f:
        json.dump({
            "org": args.org,
            "repo": args.repo,
            "timestamp": datetime.now(timezone.utc).isoformat(),
            "pr_count": len(results),
            "results": results
        }, f, indent=2)

    if results:
        scores = [r["score"] for r in results]
        print(f"\nResults saved to {args.output}")
        print(f"Summary: {len(results)} PRs, scores range {min(scores):.0f}-{max(scores):.0f}")
    else:
        print("\nNo results to save.")


if __name__ == "__main__":
    main()