#!/usr/bin/env python3
"""
Deployment Manager
Generates blue/green or rolling Kubernetes deployment manifests plus an ordered
runbook of kubectl commands, and audits existing manifests. It never talks to a
cluster itself — review the manifests and run the printed commands yourself.

Subcommands:
  deploy    --env --image [--strategy] [--health-check-url] — write manifests + runbook
  rollback  --env --to-version                              — write a rollback runbook
  analyze   --env                                           — audit manifests on disk
"""

import argparse
import json
import re
import sys
from pathlib import Path
from typing import Dict, List

DEPLOYMENT_TEMPLATE = """apiVersion: apps/v1
kind: Deployment
metadata:
  name: {name}
  namespace: {env}
  labels:
    app: {app}{slot_label}
spec:
  replicas: {replicas}
  selector:
    matchLabels:
      app: {app}{slot_label_indented}
  template:
    metadata:
      labels:
        app: {app}{slot_label_indented2}
    spec:
      containers:
        - name: app
          image: {image}
          readinessProbe:
            httpGet:
              path: {health_path}
              port: 8080
            initialDelaySeconds: 10
            periodSeconds: 5
          resources:
            requests:
              cpu: "250m"
              memory: "256Mi"
            limits:
              cpu: "500m"
              memory: "512Mi"
"""

SERVICE_TEMPLATE = """apiVersion: v1
kind: Service
metadata:
  name: {app}-svc
  namespace: {env}
spec:
  selector:
    app: {app}{slot_selector}
  ports:
    - port: 80
      targetPort: 8080
"""


def app_name_from_image(image: str) -> str:
    """ghcr.io/org/my-app:1.2.3 -> my-app"""
    repo = image.rsplit(":", 1)[0]
    return repo.rsplit("/", 1)[-1] or "app"


def render_deployment(app: str, env: str, image: str, replicas: int,
                      health_path: str, slot: str = "") -> str:
    return DEPLOYMENT_TEMPLATE.format(
        name=f"{app}-{slot}" if slot else app,
        env=env,
        app=app,
        image=image,
        replicas=replicas,
        health_path=health_path,
        slot_label=f"\n    slot: {slot}" if slot else "",
        slot_label_indented=f"\n      slot: {slot}" if slot else "",
        slot_label_indented2=f"\n        slot: {slot}" if slot else "",
    )


def cmd_deploy(args) -> Dict:
    app = args.app or app_name_from_image(args.image)
    health_path = "/healthz"
    if args.health_check_url:
        match = re.search(r"https?://[^/]+(/.*)", args.health_check_url)
        if match:
            health_path = match.group(1)

    out_dir = Path(args.output_dir) / args.env
    out_dir.mkdir(parents=True, exist_ok=True)

    written: List[str] = []
    runbook: List[str] = []

    if args.strategy == "blue-green":
        slot = args.slot
        manifest = out_dir / f"deployment-{slot}.yaml"
        manifest.write_text(
            render_deployment(app, args.env, args.image, args.replicas, health_path, slot),
            encoding="utf-8",
        )
        written.append(str(manifest))

        service = out_dir / "service.yaml"
        if not service.exists():
            # service starts pointing at the OTHER slot; traffic switches in the runbook
            other = "green" if slot == "blue" else "blue"
            service.write_text(SERVICE_TEMPLATE.format(
                app=app, env=args.env, slot_selector=f"\n    slot: {other}"), encoding="utf-8")
            written.append(str(service))

        runbook = [
            f"kubectl apply -f {manifest}",
            f"kubectl rollout status deployment/{app}-{slot} -n {args.env}",
        ]
        if args.health_check_url:
            runbook.append(f"curl -sf {args.health_check_url} || echo 'HEALTH CHECK FAILED — do not switch traffic'")
        runbook += [
            f"# switch traffic to the {slot} slot only after the checks above pass:",
            f"kubectl patch service {app}-svc -n {args.env} "
            f"-p '{{\"spec\":{{\"selector\":{{\"app\":\"{app}\",\"slot\":\"{slot}\"}}}}}}'",
        ]
    else:  # rolling
        manifest = out_dir / "deployment.yaml"
        manifest.write_text(
            render_deployment(app, args.env, args.image, args.replicas, health_path),
            encoding="utf-8",
        )
        written.append(str(manifest))

        service = out_dir / "service.yaml"
        if not service.exists():
            service.write_text(SERVICE_TEMPLATE.format(
                app=app, env=args.env, slot_selector=""), encoding="utf-8")
            written.append(str(service))

        runbook = [
            f"kubectl apply -f {manifest}",
            f"kubectl rollout status deployment/{app} -n {args.env}",
        ]
        if args.health_check_url:
            runbook.append(f"curl -sf {args.health_check_url} || kubectl rollout undo deployment/{app} -n {args.env}")

    return {
        "status": "success",
        "action": "deploy",
        "env": args.env,
        "app": app,
        "image": args.image,
        "strategy": args.strategy,
        "manifests_written": written,
        "runbook": runbook,
    }


def cmd_rollback(args) -> Dict:
    app = args.app
    runbook = [
        f"# Option 1 — pin the previous image version explicitly:",
        f"kubectl set image deployment/{app} app={app}:{args.to_version} -n {args.env}",
        f"kubectl rollout status deployment/{app} -n {args.env}",
        f"# Option 2 — revert to the previous ReplicaSet:",
        f"kubectl rollout undo deployment/{app} -n {args.env}",
        f"# Verify:",
        f"kubectl get pods -n {args.env} -l app={app}",
    ]
    return {
        "status": "success",
        "action": "rollback",
        "env": args.env,
        "app": app,
        "to_version": args.to_version,
        "runbook": runbook,
    }


def cmd_analyze(args) -> Dict:
    env_dir = Path(args.output_dir) / args.env
    deployments = []
    if env_dir.is_dir():
        for manifest in sorted(env_dir.glob("deployment*.yaml")):
            text = manifest.read_text(encoding="utf-8")
            image = re.search(r"image:\s*(\S+)", text)
            replicas = re.search(r"replicas:\s*(\d+)", text)
            slot = re.search(r"slot:\s*(\S+)", text)
            deployments.append({
                "manifest": str(manifest),
                "image": image.group(1) if image else "unknown",
                "replicas": int(replicas.group(1)) if replicas else 0,
                "slot": slot.group(1) if slot else None,
            })
    return {
        "status": "success" if deployments else "empty",
        "action": "analyze",
        "env": args.env,
        "manifest_dir": str(env_dir),
        "deployments": deployments,
    }


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        description="Generate deployment manifests and runbooks (blue/green or rolling)."
    )
    sub = parser.add_subparsers(dest="command", required=True)

    deploy = sub.add_parser("deploy", help="Generate deployment manifests + runbook")
    deploy.add_argument("--env", required=True, help="Target environment / namespace")
    deploy.add_argument("--image", required=True, help="Container image (repo:tag)")
    deploy.add_argument("--strategy", default="rolling", choices=["blue-green", "rolling"])
    deploy.add_argument("--health-check-url", help="Health check URL gating traffic switch")
    deploy.add_argument("--app", help="App name (default: derived from image)")
    deploy.add_argument("--slot", default="blue", choices=["blue", "green"],
                        help="Slot to deploy into (blue-green only)")
    deploy.add_argument("--replicas", type=int, default=3)
    deploy.add_argument("--output-dir", default="./deploy", help="Manifest output directory")

    rollback = sub.add_parser("rollback", help="Generate a rollback runbook")
    rollback.add_argument("--env", required=True)
    rollback.add_argument("--to-version", required=True, help="Version to roll back to")
    rollback.add_argument("--app", default="app", help="App / deployment name")

    analyze = sub.add_parser("analyze", help="Audit deployment manifests on disk")
    analyze.add_argument("--env", required=True)
    analyze.add_argument("--output-dir", default="./deploy", help="Manifest directory")

    for p in (deploy, rollback, analyze):
        p.add_argument("--verbose", "-v", action="store_true", help="Enable verbose output")
        p.add_argument("--json", action="store_true", help="Output results as JSON")
        p.add_argument("--output", "-o", help="Write JSON results to this file")
    return parser


def main():
    # support the documented `--analyze --env=...` flag form as an alias
    argv = ["analyze" if a == "--analyze" else a for a in sys.argv[1:]]
    args = build_parser().parse_args(argv)

    handlers = {"deploy": cmd_deploy, "rollback": cmd_rollback, "analyze": cmd_analyze}
    results = handlers[args.command](args)

    print(f"🚀 {results['action']} ({results['env']}) — status: {results['status']}")
    for manifest in results.get("manifests_written", []):
        print(f"✓ Wrote {manifest}")
    for dep in results.get("deployments", []):
        slot = f" slot={dep['slot']}" if dep["slot"] else ""
        print(f"  - {dep['manifest']}: image={dep['image']} replicas={dep['replicas']}{slot}")
    if results.get("runbook"):
        print("\nRunbook — review, then execute in order:")
        for step in results["runbook"]:
            print(f"  {step}")

    if args.json or args.output:
        output = json.dumps(results, indent=2)
        if args.output:
            Path(args.output).write_text(output, encoding="utf-8")
            print(f"Results written to {args.output}")
        else:
            print(output)


if __name__ == "__main__":
    main()