#!/usr/bin/env python3
"""
Operator Ingress → Gitea Mutation Gate

Transport-agnostic, idempotent gate for all operator-originated Gitea mutations.
This is the single canonical write path for create/comment/assign/merge/close actions.

Design invariants:
1. Every command gets a deterministic idempotency key.
2. Before executing, the gate checks Gitea for evidence of prior execution.
3. After executing, the gate records proof of execution (via comment trail or local ledger).
4. Replay of the same command returns the previously generated result without double-writing.
"""

import hashlib
import json
import os
import urllib.request
from dataclasses import dataclass, asdict
from datetime import datetime
from pathlib import Path
from typing import Optional, Dict, Any, List


# ---------------------------------------------------------------------------
# Configuration
# ---------------------------------------------------------------------------
GITEA_URL = os.environ.get("GITEA_URL", "https://forge.alexanderwhitestone.com")
TOKEN_PATHS = ["/root/.gitea_token", os.path.expanduser("~/.gitea_token")]
_LEDGER_PATH = Path(os.environ.get("GATE_LEDGER_PATH", "/root/.operator_gate_ledger.jsonl"))


# ---------------------------------------------------------------------------
# Data models
# ---------------------------------------------------------------------------
@dataclass(frozen=True)
class Command:
    source: str           # e.g. "nostr:npub10trqk..." or "matrix:@alex:..."
    action: str           # "create_issue" | "add_comment" | "close_issue" | "merge_pr" | "assign_issue"
    repo: str             # "Timmy_Foundation/timmy-config"
    payload: Dict[str, Any]
    timestamp_utc: str    # ISO-8601, used for idempotency windowing

    def idempotency_key(self) -> str:
        """Deterministic key: replay-safe, collision-resistant."""
        payload_str = json.dumps(self.payload, sort_keys=True, ensure_ascii=True)
        raw = f"{self.source}:{self.action}:{self.repo}:{payload_str}"
        return hashlib.sha256(raw.encode()).hexdigest()[:32]


@dataclass
class Ack:
    success: bool
    idempotency_key: str
    gitea_url: Optional[str]
    gitea_number: Optional[int]
    message: str
    prior_execution: bool
    executed_at: Optional[str] = None


# ---------------------------------------------------------------------------
# Low-level Gitea API
# ---------------------------------------------------------------------------
def _load_token() -> str:
    for path in TOKEN_PATHS:
        try:
            with open(path) as f:
                token = f.read().strip()
            if token:
                return token
        except FileNotFoundError:
            pass
    raise RuntimeError("Gitea token not found")


def _headers() -> Dict[str, str]:
    return {"Authorization": f"token {_load_token()}", "Content-Type": "application/json"}


def _api_request(method: str, path: str, data: Optional[Dict] = None) -> Dict[str, Any]:
    url = f"{GITEA_URL}/api/v1{path}"
    body = json.dumps(data).encode() if data else None
    req = urllib.request.Request(url, data=body, headers=_headers(), method=method)
    with urllib.request.urlopen(req, timeout=20) as resp:
        text = resp.read().decode()
        return json.loads(text) if text else {"status": resp.status}


def _api_get(path: str) -> Any:
    url = f"{GITEA_URL}/api/v1{path}"
    req = urllib.request.Request(url, headers=_headers())
    with urllib.request.urlopen(req, timeout=20) as resp:
        return json.loads(resp.read().decode())


# ---------------------------------------------------------------------------
# Ledger (local idempotency cache)
# ---------------------------------------------------------------------------
def _ledger_load() -> Dict[str, Dict]:
    if not _LEDGER_PATH.exists():
        return {}
    entries = {}
    with open(_LEDGER_PATH, "r") as f:
        for line in f:
            line = line.strip()
            if not line:
                continue
            try:
                entry = json.loads(line)
                entries[entry["idempotency_key"]] = entry
            except (json.JSONDecodeError, KeyError):
                continue
    return entries


def _ledger_append(entry: Dict):
    _LEDGER_PATH.parent.mkdir(parents=True, exist_ok=True)
    with open(_LEDGER_PATH, "a") as f:
        f.write(json.dumps(entry, ensure_ascii=True) + "\n")


# ---------------------------------------------------------------------------
# Gitea-side idempotency probes
# ---------------------------------------------------------------------------
def _probe_issue_by_title(repo: str, title: str, window_hours: int = 24) -> Optional[Dict]:
    """Search recent open issues for a duplicate title to avoid double-create."""
    try:
        issues = _api_get(f"/repos/{repo}/issues?state=open&limit=20")
        for issue in issues:
            if issue.get("title") == title:
                return issue
        # Also check recently closed
        issues = _api_get(f"/repos/{repo}/issues?state=closed&limit=10")
        for issue in issues:
            if issue.get("title") == title:
                created = issue.get("created_at", "")
                # naive window check
                if created and "T" in created:
                    return issue
    except Exception:
        pass
    return None


def _probe_comment_by_fingerprint(repo: str, issue_num: int, fingerprint: str) -> Optional[Dict]:
    """Scan recent comments for the idempotency fingerprint."""
    try:
        comments = _api_get(f"/repos/{repo}/issues/{issue_num}/comments?limit=50")
        for comment in comments:
            body = comment.get("body", "")
            if fingerprint in body:
                return comment
    except Exception:
        pass
    return None


# ---------------------------------------------------------------------------
# Gate execution
# ---------------------------------------------------------------------------
class GiteaGate:
    """The single canonical write path."""

    def execute(self, cmd: Command) -> Ack:
        key = cmd.idempotency_key()
        ledger = _ledger_load()

        # 1. Local ledger hit
        if key in ledger:
            entry = ledger[key]
            return Ack(
                success=True,
                idempotency_key=key,
                gitea_url=entry.get("gitea_url"),
                gitea_number=entry.get("gitea_number"),
                message=entry.get("message", "Replay: already executed."),
                prior_execution=True,
                executed_at=entry.get("executed_at"),
            )

        # 2. Execute
        handler = getattr(self, f"_handle_{cmd.action}", None)
        if handler is None:
            return Ack(
                success=False,
                idempotency_key=key,
                gitea_url=None,
                gitea_number=None,
                message=f"Unsupported action: {cmd.action}",
                prior_execution=False,
            )

        try:
            ack = handler(cmd, key)
            _ledger_append({
                "idempotency_key": ack.idempotency_key,
                "action": cmd.action,
                "repo": cmd.repo,
                "gitea_url": ack.gitea_url,
                "gitea_number": ack.gitea_number,
                "message": ack.message,
                "executed_at": datetime.utcnow().isoformat() + "Z",
            })
            return ack
        except Exception as e:
            return Ack(
                success=False,
                idempotency_key=key,
                gitea_url=None,
                gitea_number=None,
                message=f"Execution error: {e}",
                prior_execution=False,
            )

    # -------------------------------------------------------------------
    # Action handlers
    # -------------------------------------------------------------------
    def _handle_create_issue(self, cmd: Command, key: str) -> Ack:
        title = cmd.payload.get("title", "")
        body = cmd.payload.get("body", "")
        assignees = cmd.payload.get("assignees")
        labels = cmd.payload.get("labels")

        # Probe Gitea for duplicate title
        dup = _probe_issue_by_title(cmd.repo, title)
        if dup:
            return Ack(
                success=True,
                idempotency_key=key,
                gitea_url=dup.get("html_url"),
                gitea_number=dup.get("number"),
                message=f"Duplicate detected: issue #{dup['number']} already exists.",
                prior_execution=True,
            )

        data = {
            "title": title,
            "body": f"{body}\n\n---\n*Operator ingress via {cmd.source} — gate-key: `{key}`*",
        }
        if assignees:
            data["assignees"] = assignees
        if labels:
            data["labels"] = labels

        result = _api_request("POST", f"/repos/{cmd.repo}/issues", data)
        url = result.get("html_url", f"{GITEA_URL}/{cmd.repo}/issues/{result['number']}")
        return Ack(
            success=True,
            idempotency_key=key,
            gitea_url=url,
            gitea_number=result.get("number"),
            message=f"Created issue #{result['number']}: {result['title']}",
            prior_execution=False,
        )

    def _handle_add_comment(self, cmd: Command, key: str) -> Ack:
        issue_num = int(cmd.payload["issue_num"])
        body = cmd.payload["body"]

        # Probe for fingerprint
        dup = _probe_comment_by_fingerprint(cmd.repo, issue_num, key)
        if dup:
            return Ack(
                success=True,
                idempotency_key=key,
                gitea_url=dup.get("html_url"),
                gitea_number=issue_num,
                message=f"Duplicate detected: comment already posted.",
                prior_execution=True,
            )

        result = _api_request(
            "POST",
            f"/repos/{cmd.repo}/issues/{issue_num}/comments",
            {"body": f"{body}\n\n---\n*gate-key: `{key}`*"},
        )
        url = result.get("html_url", f"{GITEA_URL}/{cmd.repo}/issues/{issue_num}#issuecomment-{result.get('id', '')}")
        return Ack(
            success=True,
            idempotency_key=key,
            gitea_url=url,
            gitea_number=issue_num,
            message=f"Added comment to issue #{issue_num}",
            prior_execution=False,
        )

    def _handle_close_issue(self, cmd: Command, key: str) -> Ack:
        issue_num = int(cmd.payload["issue_num"])
        # Check if already closed
        issue = _api_get(f"/repos/{cmd.repo}/issues/{issue_num}")
        if issue.get("state") == "closed":
            return Ack(
                success=True,
                idempotency_key=key,
                gitea_url=issue.get("html_url"),
                gitea_number=issue_num,
                message=f"Issue #{issue_num} already closed.",
                prior_execution=True,
            )

        result = _api_request(
            "PATCH",
            f"/repos/{cmd.repo}/issues/{issue_num}",
            {"state": "closed"},
        )
        # Add closure proof comment
        try:
            _api_request(
                "POST",
                f"/repos/{cmd.repo}/issues/{issue_num}/comments",
                {"body": f"Closed via operator ingress ({cmd.source}) — gate-key: `{key}`"},
            )
        except Exception:
            pass

        return Ack(
            success=True,
            idempotency_key=key,
            gitea_url=result.get("html_url"),
            gitea_number=issue_num,
            message=f"Closed issue #{issue_num}",
            prior_execution=False,
        )

    def _handle_assign_issue(self, cmd: Command, key: str) -> Ack:
        issue_num = int(cmd.payload["issue_num"])
        assignees = cmd.payload.get("assignees", [])
        result = _api_request(
            "PATCH",
            f"/repos/{cmd.repo}/issues/{issue_num}",
            {"assignees": assignees},
        )
        return Ack(
            success=True,
            idempotency_key=key,
            gitea_url=result.get("html_url"),
            gitea_number=issue_num,
            message=f"Assigned issue #{issue_num} to {', '.join(assignees)}",
            prior_execution=False,
        )

    def _handle_merge_pr(self, cmd: Command, key: str) -> Ack:
        pr_num = int(cmd.payload["pr_num"])
        # Check if already merged
        pr = _api_get(f"/repos/{cmd.repo}/pulls/{pr_num}")
        if pr.get("merged"):
            return Ack(
                success=True,
                idempotency_key=key,
                gitea_url=pr.get("html_url"),
                gitea_number=pr_num,
                message=f"PR #{pr_num} already merged.",
                prior_execution=True,
            )

        result = _api_request(
            "POST",
            f"/repos/{cmd.repo}/pulls/{pr_num}/merge",
            {"Do": "merge", "delete_branch_after_merge": False},
        )
        return Ack(
            success=True,
            idempotency_key=key,
            gitea_url=pr.get("html_url"),
            gitea_number=pr_num,
            message=f"Merged PR #{pr_num}",
            prior_execution=False,
        )


# ---------------------------------------------------------------------------
# Convenience helpers for adapters
# ---------------------------------------------------------------------------
def create_issue(source: str, repo: str, title: str, body: str = "", assignees: Optional[List[str]] = None, labels: Optional[List[str]] = None) -> Ack:
    return GiteaGate().execute(Command(
        source=source,
        action="create_issue",
        repo=repo,
        payload={"title": title, "body": body, "assignees": assignees or [], "labels": labels or []},
        timestamp_utc=datetime.utcnow().isoformat() + "Z",
    ))


def add_comment(source: str, repo: str, issue_num: int, body: str) -> Ack:
    return GiteaGate().execute(Command(
        source=source,
        action="add_comment",
        repo=repo,
        payload={"issue_num": issue_num, "body": body},
        timestamp_utc=datetime.utcnow().isoformat() + "Z",
    ))


def close_issue(source: str, repo: str, issue_num: int) -> Ack:
    return GiteaGate().execute(Command(
        source=source,
        action="close_issue",
        repo=repo,
        payload={"issue_num": issue_num},
        timestamp_utc=datetime.utcnow().isoformat() + "Z",
    ))


def assign_issue(source: str, repo: str, issue_num: int, assignees: List[str]) -> Ack:
    return GiteaGate().execute(Command(
        source=source,
        action="assign_issue",
        repo=repo,
        payload={"issue_num": issue_num, "assignees": assignees},
        timestamp_utc=datetime.utcnow().isoformat() + "Z",
    ))


def merge_pr(source: str, repo: str, pr_num: int) -> Ack:
    return GiteaGate().execute(Command(
        source=source,
        action="merge_pr",
        repo=repo,
        payload={"pr_num": pr_num},
        timestamp_utc=datetime.utcnow().isoformat() + "Z",
    ))