#!/usr/bin/env python3
"""Generate Terraform dynu_dns_record resources/import commands from Dynu inventory outputs."""

from __future__ import annotations

import argparse
import json
import re
import subprocess
import sys
from pathlib import Path

SCRIPT_PATH = Path(__file__).resolve()
TF_ROOT = SCRIPT_PATH.parents[1]
GENERATED_DIR = TF_ROOT / "generated"
TF_FILE = GENERATED_DIR / "dynu_dns_records.generated.tf"
IMPORT_SCRIPT = GENERATED_DIR / "import-dynu-dns-records.sh"
INVENTORY_FILE = GENERATED_DIR / "dynu_dns_records_inventory.json"

HEADER_TF = """# ---------------------------------------------------------------------------
# GENERATED FILE - REVIEW BEFORE USE
#
# Generated from Dynu brownfield DNS inventory.
# Do not blindly apply this file to production DNS.
# Import records into Terraform state before allowing Terraform to manage them.
# ---------------------------------------------------------------------------
"""

HEADER_SH = """#!/usr/bin/env bash
# ---------------------------------------------------------------------------
# GENERATED FILE - REVIEW BEFORE USE
#
# Imports existing Dynu DNS records into Terraform state.
# Does not apply changes.
# ---------------------------------------------------------------------------
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
TF_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
cd "${TF_ROOT}"

# Re-running imports will fail for resources already in state.
# This script skips imports when state already contains the resource address.
"""

OPTIONAL_FIELDS = ["group", "host", "priority", "weight", "port", "flags", "tag", "value", "node_name"]


def run_terraform_output() -> dict:
    if not (TF_ROOT / ".terraform").exists():
        raise RuntimeError("Terraform is not initialized in infrastructure/terraform/dynu. Run: terraform init")

    cmd = ["terraform", "output", "-json"]
    proc = subprocess.run(cmd, cwd=TF_ROOT, capture_output=True, text=True)
    if proc.returncode != 0:
        raise RuntimeError(f"Failed to run {' '.join(cmd)}:\n{proc.stderr.strip()}")
    return json.loads(proc.stdout)


def tf_name(record: dict) -> str:
    base = f"{record.get('hostname', '')}_{record.get('record_type', '')}_{record.get('id', '')}".lower()
    base = base.replace("*", "wildcard")
    base = re.sub(r"[^a-z0-9_]+", "_", base)
    base = re.sub(r"_+", "_", base).strip("_")
    if not base or not re.match(r"^[a-z]", base):
        base = f"record_{base}" if base else "record"
    if not base.endswith(str(record.get("id", ""))):
        base = f"{base}_{record.get('id', '')}"
    return base


def hcl_value(value):
    if isinstance(value, bool):
        return "true" if value else "false"
    if isinstance(value, (int, float)):
        return str(value)
    return json.dumps(value)


def generate_resources(records: list[dict]) -> str:
    chunks = [HEADER_TF.rstrip(), ""]
    for rec in records:
        name = tf_name(rec)
        lines = [f'resource "dynu_dns_record" "{name}" {{']
        lines.append(f"  hostname    = {hcl_value(rec.get('hostname'))}")
        lines.append(f"  record_type = {hcl_value(rec.get('record_type'))}")
        if rec.get("ttl") is not None:
            lines.append(f"  ttl         = {hcl_value(rec.get('ttl'))}")
        if rec.get("enabled") is not None:
            lines.append(f"  enabled     = {hcl_value(rec.get('enabled'))}")

        content = rec.get("content")
        rtype = str(rec.get("record_type", "")).upper()
        if content in (None, "") and rtype in {"A", "AAAA"}:
            lines.append("  dynamic     = true")
        elif content not in (None, ""):
            lines.append(f"  content     = {hcl_value(content)}")

        for field in OPTIONAL_FIELDS:
            value = rec.get(field)
            if value not in (None, ""):
                lines.append(f"  {field.ljust(11)}= {hcl_value(value)}")

        lines.extend([
            "",
            "  lifecycle {",
            "    prevent_destroy = true",
            "  }",
            "}",
            "",
        ])
        chunks.extend(lines)
    return "\n".join(chunks).rstrip() + "\n"


def generate_import_script(records: list[dict]) -> str:
    lines = [HEADER_SH.rstrip(), ""]
    for rec in records:
        name = tf_name(rec)
        import_id = f"{rec['domain_id']}/{rec['id']}"
        addr = f"dynu_dns_record.{name}"
        lines.append(f"if terraform state show '{addr}' >/dev/null 2>&1; then")
        lines.append(f"  echo 'Skipping already imported: {addr}'")
        lines.append("else")
        lines.append(f"  terraform import '{addr}' '{import_id}'")
        lines.append("fi")
        lines.append("")
    return "\n".join(lines).rstrip() + "\n"


def write_file(path: Path, content: str, dry_run: bool, overwrite: bool) -> None:
    if path.exists() and not overwrite:
        raise RuntimeError(f"Refusing to overwrite existing file: {path}. Re-run with --overwrite.")
    if dry_run:
        print(f"[dry-run] Would write {path}")
        return
    path.write_text(content, encoding="utf-8")
    print(f"Wrote {path}")


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--dry-run", action="store_true", help="Print intended output paths without writing files.")
    parser.add_argument("--overwrite", "--force", action="store_true", dest="overwrite", help="Overwrite existing generated files.")
    args = parser.parse_args()

    try:
        out = run_terraform_output()
        records = out["dynu_dns_records"]["value"]
        if not isinstance(records, list):
            raise RuntimeError("terraform output dynu_dns_records did not return a list.")

        GENERATED_DIR.mkdir(parents=True, exist_ok=True)
        write_file(INVENTORY_FILE, json.dumps(records, indent=2, sort_keys=True) + "\n", args.dry_run, args.overwrite)
        write_file(TF_FILE, generate_resources(records), args.dry_run, args.overwrite)
        write_file(IMPORT_SCRIPT, generate_import_script(records), args.dry_run, args.overwrite)
        if not args.dry_run:
            IMPORT_SCRIPT.chmod(0o755)
        return 0
    except Exception as exc:  # noqa: BLE001
        print(f"Error: {exc}", file=sys.stderr)
        return 1


if __name__ == "__main__":
    raise SystemExit(main())