#!/usr/bin/env python3

"""Make everything in the room bigger or smaller, once.

UI_SCALE is the display's scale factor, so it scales the browser, VLC, the
bar and every dialog together rather than each of them separately. Plasma
owns display configuration, so this asks Plasma's own tool to do it — which
is the whole of what replaced the compositor-specific version.
"""

import json
import os
import subprocess
import sys

sys.path.insert(0, "/usr/local/lib/ekklesia-classroom")
sys.path.insert(
    0,
    os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "lib"),
)

from classroom_config import read_device_config, ui_scale  # noqa: E402


def outputs():
    """Every connected display, by name.

    The JSON form rather than the human one: kscreen-doctor's plain output
    is full of terminal colour codes, and a regular expression over it
    silently matched nothing.
    """
    try:
        listing = subprocess.run(
            ["kscreen-doctor", "-j"],
            capture_output=True, text=True, timeout=20, check=False,
        ).stdout
        found = json.loads(listing or "{}").get("outputs") or []
    except (OSError, subprocess.SubprocessError, ValueError) as error:
        print(f"classroom-scale: {error}", file=sys.stderr)
        return []

    return [
        output["name"] for output in found
        if output.get("name") and output.get("connected", True)
    ]


def main():
    # classroom_config clamps a nonsense or out-of-range value rather than
    # obeying it, so a mistyped UI_SCALE cannot leave a room unusable.
    scale = ui_scale(read_device_config())
    found = outputs()

    if not found:
        print("classroom-scale: no outputs", file=sys.stderr)
        return 0

    for output in found:
        result = subprocess.run(
            ["kscreen-doctor", f"output.{output}.scale.{scale}"],
            capture_output=True, text=True, timeout=20, check=False,
        )

        if result.returncode == 0:
            print(f"classroom-scale: {output} scale {scale}")
        else:
            print(f"classroom-scale: {output}: {result.stderr.strip()}",
                  file=sys.stderr)

    return 0


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