"""Render the MAS facility manifest for a power state.

This file does not talk to the cluster. power.sh and apply.sh do.
"""

from __future__ import annotations

import sys

SWITCHABLE = ("mas-mx", "mas-statute")


def render(manifest: str, image: str, power: str) -> str:
    """Return the manifest with IMAGE filled in and replicas set from power.

    `on` keeps one replica of each switchable Deployment. `off` sets both
    to zero. Services, the evidence volume, the Ingress, and the
    ExternalSecret are copied through unchanged.
    """
    if power not in ("on", "off"):
        raise ValueError(f"power must be on or off, got {power!r}")
    if not image or any(ch.isspace() for ch in image):
        raise ValueError("image must be a single token")
    if "image: IMAGE" not in manifest:
        raise ValueError("manifest has no image: IMAGE placeholder")

    rendered = manifest.replace("image: IMAGE", f"image: {image}")
    docs = rendered.split("\n---\n")
    seen: set[str] = set()
    out: list[str] = []
    for doc in docs:
        name = _deployment_name(doc)
        if name in SWITCHABLE:
            seen.add(name)
            doc = _set_replicas(doc, 0 if power == "off" else 1)
        out.append(doc)
    missing = [name for name in SWITCHABLE if name not in seen]
    if missing:
        raise ValueError("manifest is missing Deployments: " + ", ".join(missing))
    return "\n---\n".join(out)


def _deployment_name(doc: str) -> str | None:
    kind = None
    name = None
    for line in doc.splitlines():
        if line.startswith("kind:"):
            kind = line.split(":", 1)[1].strip()
        elif line.startswith("  name:") and name is None:
            name = line.split(":", 1)[1].strip()
    if kind == "Deployment":
        return name
    return None


def _set_replicas(doc: str, count: int) -> str:
    lines = doc.splitlines(keepends=True)
    found = 0
    out = []
    for line in lines:
        if line.startswith("  replicas:"):
            found += 1
            newline = "\n" if line.endswith("\n") else ""
            out.append(f"  replicas: {count}{newline}")
        else:
            out.append(line)
    if found != 1:
        raise ValueError(f"expected one replicas field, found {found}")
    return "".join(out)


def main(argv: list[str]) -> int:
    if len(argv) != 4 or argv[1] != "render":
        print("usage: facility.py render IMAGE on|off", file=sys.stderr)
        return 2
    sys.stdout.write(render(sys.stdin.read(), argv[2], argv[3]))
    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv))