#!/usr/bin/env bash

# Display configuration.
#
# This is the only setting in Panama that can leave the user unable to SEE the
# screen well enough to undo it: a mode the panel cannot show, or a scale that
# makes everything unreadable, is not recoverable through the UI that caused it.
#
# So the property under test is not "can it change the resolution" but "does an
# unconfirmed change always come back". A regression here is not a broken
# feature, it is a user staring at a blank monitor.
#
#   * an unconfirmed change reverts on its own, and stores nothing
#   * a confirmed change is what writes to the settings store
#   * a mode, scale, rotation, or output the compositor did not offer is refused
#     before anything is applied
#
# The compositor is the live one -- there is no way to test this otherwise --
# but preferences are isolated, and every path restores the display it started
# from.

set -euo pipefail

repo_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
harness="$repo_dir/config/dot/quickshell/displays-harness.qml"
config_home="$(mktemp -d /tmp/panama-displays-config.XXXXXX)"

fail() {
    printf 'displays contract: %s\n' "$1" >&2
    exit 1
}

run() { XDG_CONFIG_HOME="$config_home" qs -p "$harness" "$@"; }
status() { run ipc call displays-test status; }

original_mode=""
original_scale=""
original_transform=""

restore() {
    # Through hyprctl rather than the harness: if the harness apply path is what
    # is broken, the daily-driver display must still come back.
    if [[ -n "$original_mode" ]]; then
        hyprctl eval "hl.monitor({ output = \"$monitor_name\", mode = \"$original_mode\", scale = $original_scale, transform = $original_transform })" >/dev/null 2>&1 || true
    fi
    # Kill by PID, never `pkill -f displays-harness`: that pattern also matches
    # any shell whose command line contains this script's text, which includes
    # the invoking shell itself.
    [[ -n "${harness_pid:-}" ]] && kill "$harness_pid" >/dev/null 2>&1 || true
    rm -rf "$config_home"
}
trap restore EXIT

XDG_CONFIG_HOME="$config_home" qs -p "$harness" --daemonize >/dev/null
harness_pid=""
for _ in $(seq 1 40); do
    run ipc show 2>/dev/null | rg -q '^target displays-test$' && break
    sleep 0.1
done
run ipc show 2>/dev/null | rg -q '^target displays-test$' || fail 'test IPC target did not start'
harness_pid="$(run list | awk '/Process ID:/ { print $3; exit }')"

for _ in $(seq 1 50); do
    [[ "$(status | jq -r .count)" != "0" ]] && break
    sleep 0.1
done

state="$(status)"
monitor_name="$(jq -r .name <<<"$state")"
[[ -n "$monitor_name" ]] || fail "no display was detected: $state"
original_mode="$(jq -r '"\(.width)x\(.height)@\(.refresh)"' <<<"$state")"
original_scale="$(jq -r .scale <<<"$state")"
original_transform="$(jq -r .transform <<<"$state")"

[[ "$(jq -r .modes <<<"$state")" -gt 0 ]] || fail 'the display reported no usable modes'

# ── Anything the compositor did not offer is refused before applying ─────────
while IFS= read -r kind; do
    [[ "$(run ipc call displays-test applyBad "$kind")" == "false" ]] \
        || fail "an invalid $kind was accepted"
    [[ "$(status | jq -r .awaiting)" == "false" ]] \
        || fail "an invalid $kind left a change pending"
done <<'KINDS'
mode
scale
transform
output
KINDS

# The display must not have moved for any of those.
now="$(status)"
[[ "$(jq -r .scale <<<"$now")" == "$original_scale" ]] || fail 'a refused change still altered the scale'

# ── An unconfirmed change reverts on its own and stores nothing ──────────────
target_scale=$(awk -v s="$original_scale" 'BEGIN { print (s == 1.25) ? 1.5 : 1.25 }')
[[ "$(run ipc call displays-test applyScale "$target_scale")" == "true" ]] \
    || fail 'a valid scale change was refused'

applied=false
for _ in $(seq 1 30); do
    [[ "$(hyprctl -j monitors | jq -r '.[0].scale')" == "$target_scale" ]] && { applied=true; break; }
    sleep 0.2
done
[[ "$applied" == true ]] || fail 'the scale change never reached the compositor'
[[ "$(status | jq -r .awaiting)" == "true" ]] || fail 'an applied change is not awaiting confirmation'

# Wait out the countdown. This is the whole point of the contract.
reverted=false
for _ in $(seq 1 120); do
    if [[ "$(hyprctl -j monitors | jq -r '.[0].scale')" == "$original_scale" ]]; then
        reverted=true
        break
    fi
    sleep 0.5
done
[[ "$reverted" == true ]] || fail 'an unconfirmed change did NOT revert -- this would strand a user on an unreadable display'
[[ "$(status | jq -r .awaiting)" == "false" ]] || fail 'the pending state survived the revert'
[[ "$(status | jq -r .overridden)" == "false" ]] || fail 'an unconfirmed change was written to the settings store'

# ── A confirmed change is what writes ────────────────────────────────────────
run ipc call displays-test applyScale "$target_scale" >/dev/null
sleep 1
run ipc call displays-test confirmChange >/dev/null
sleep 0.6
[[ "$(status | jq -r .awaiting)" == "false" ]] || fail 'confirming did not clear the pending state'
[[ "$(status | jq -r .overridden)" == "true" ]] || fail 'confirming did not store the change'

store="$config_home/panama/settings.json"
jq -e --arg m "$monitor_name" '.displays[$m].scale != null' "$store" >/dev/null \
    || fail 'the confirmed change is not in the settings store'

# ── Forgetting clears it ─────────────────────────────────────────────────────
run ipc call displays-test forget >/dev/null
sleep 0.6
[[ "$(status | jq -r .overridden)" == "false" ]] || fail 'forget did not clear the stored display setting'

trap - EXIT
restore
printf 'displays contract: PASS\n'