#!/usr/bin/env bash

# Refresh the agent usage records the bar panel watches.
#
# Each panama-agent-usage-<agent> collector prints one display-ready JSON
# record; this runs the enabled ones in parallel and writes their output to
# $XDG_STATE_HOME/panama/agents/usage/<agent>.json. Adding an agent is adding a
# collector -- the panel picks up any record that appears in that directory, and
# no QML changes.
#
# Adapted from Omarchy (bin/omarchy-agent-usage-update).
#
# Copyright (c) David Heinemeier Hansson
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# ── Why this reads settings.json rather than being told ──────────────────────
#
# Per-agent collection is a preference, and a preference is read at the moment
# it matters -- the same rule the power button follows. A collector the user
# turned off must not run at all: it is the thing that reads a credential file
# and makes a network call, so "off" has to mean "no process", not "a process
# whose output is discarded".
#
# ── Why a disabled agent's record is deleted ─────────────────────────────────
#
# The panel watches the directory. Leaving yesterday's record behind after the
# collector is switched off would keep showing numbers nothing is refreshing,
# which is worse than an empty tab.

set -uo pipefail

self_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

# Seams. The contract points all three somewhere hermetic; nothing else does.
COLLECTOR_DIR="${PANAMA_AGENT_USAGE_COLLECTORS:-$self_dir}"
USAGE_DIR="${PANAMA_AGENT_USAGE_DIR:-${XDG_STATE_HOME:-$HOME/.local/state}/panama/agents/usage}"
SETTINGS="${PANAMA_SETTINGS:-${XDG_CONFIG_HOME:-$HOME/.config}/panama/settings.json}"

command -v jq >/dev/null 2>&1 || {
    printf 'panama-agent-usage-update: jq is required\n' >&2
    exit 1
}

mkdir -p "$USAGE_DIR" || exit 1

flags=()
only=()

while (( $# > 0 )); do
    case "$1" in
        --force | --limits-only) flags+=("$1") ;;
        --help | -h)
            printf 'usage: panama-agent-usage-update [--force] [--limits-only] [agent...]\n'
            exit 0
            ;;
        -*)
            printf 'panama-agent-usage-update: unknown option %s\n' "$1" >&2
            exit 2
            ;;
        *) only+=("$1") ;;
    esac
    shift
done

# `.key // true` is wrong here: jq's alternative operator fires on false as well
# as on null, so a collector the user switched off would read as enabled. Absent
# is the only case that means "use the default".
enabled() {
    local agent="$1" key answer
    key="agentUsage$(tr '[:lower:]' '[:upper:]' <<<"${agent:0:1}")${agent:1}"
    [[ -r "$SETTINGS" ]] || return 0
    answer="$(jq -r --arg key "$key" \
        'if has($key) then (.[$key] | tostring) else "true" end' "$SETTINGS" 2>/dev/null)" || return 0
    [[ "$answer" == "true" ]]
}

requested() {
    local agent="$1" candidate
    (( ${#only[@]} == 0 )) && return 0
    for candidate in "${only[@]}"; do
        [[ "$candidate" == "$agent" ]] && return 0
    done
    return 1
}

# A record is replaced only by a whole, parseable one. A collector that dies
# halfway, or prints a stack trace, leaves the previous numbers standing rather
# than blanking the panel: mktemp + mv makes the swap atomic, so a reader never
# sees a half-written file, and the jq gate makes sure the thing being moved
# into place is a record at all.
collect() {
    local collector="$1" agent="$2" record tmp
    if ! record="$("$collector" "${flags[@]}" 2>/dev/null)" \
        || [[ -z "$record" ]] \
        || ! jq -e . >/dev/null 2>&1 <<<"$record"; then
        printf 'panama-agent-usage-update: the %s collector produced no usable record\n' "$agent" >&2
        return 1
    fi
    tmp="$(mktemp "$USAGE_DIR/.$agent.XXXXXX")" || return 1
    printf '%s\n' "$record" >"$tmp" || { rm -f "$tmp"; return 1; }
    chmod 644 "$tmp"
    mv "$tmp" "$USAGE_DIR/$agent.json"
}

pids=()
status=0

for collector in "$COLLECTOR_DIR"/panama-agent-usage-*; do
    [[ -x "$collector" ]] || continue
    agent="${collector##*/panama-agent-usage-}"
    [[ "$agent" == "update" ]] && continue
    requested "$agent" || continue
    if ! enabled "$agent"; then
        rm -f "$USAGE_DIR/$agent.json"
        continue
    fi
    collect "$collector" "$agent" &
    pids+=($!)
done

for pid in "${pids[@]}"; do
    wait "$pid" || status=1
done

exit "$status"