#!/usr/bin/env bash

# This file is part of I38.
#
# I38 is free software: you can redistribute it and/or modify it under the terms
# of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.

set -u

remoteUrl="${I38_UPDATE_REMOTE_URL:-https://git.stormux.org/storm/I38}"
remoteRef="${I38_UPDATE_REMOTE_REF:-refs/heads/master}"
initialDelay="${I38_UPDATE_INITIAL_DELAY:-90}"
checkInterval="${I38_UPDATE_CHECK_INTERVAL:-21600}"
notifyInterval="${I38_UPDATE_NOTIFY_INTERVAL:-604800}"
networkTimeout="${I38_UPDATE_NETWORK_TIMEOUT:-20}"

scriptDir="$(unset CDPATH; cd -- "$(dirname -- "$0")" && pwd)"
i3Dir="$(dirname -- "$scriptDir")"
versionFile="${I38_VERSION_FILE:-${i3Dir}/i38-version}"
stateDir="${XDG_STATE_HOME:-${HOME}/.local/state}/I38"
notifyState="${stateDir}/update-check-notified"
runtimeDir="${XDG_RUNTIME_DIR:-/tmp}"
lockDir="${runtimeDir}/i38-update-check"

valid_commit() {
    [[ "${1:-}" =~ ^[0-9a-fA-F]{40}$ ]]
}

read_installed_commit() {
    local commit

    [[ -r "$versionFile" ]] || return 1
    IFS= read -r commit < "$versionFile" || return 1
    valid_commit "$commit" || return 1
    printf '%s\n' "$commit"
}

read_remote_commit() {
    local output commit

    if command -v timeout > /dev/null; then
        output="$(timeout "$networkTimeout" git ls-remote "$remoteUrl" "$remoteRef" 2> /dev/null)" || return 1
    else
        output="$(git ls-remote "$remoteUrl" "$remoteRef" 2> /dev/null)" || return 1
    fi
    commit="${output%%[[:space:]]*}"
    valid_commit "$commit" || return 1
    printf '%s\n' "$commit"
}

already_notified() {
    local remoteCommit="$1"
    local lastCommit lastTime now

    [[ -r "$notifyState" ]] || return 1
    {
        IFS= read -r lastCommit
        IFS= read -r lastTime
    } < "$notifyState" || return 1

    [[ "$lastCommit" == "$remoteCommit" ]] || return 1
    [[ "$lastTime" =~ ^[0-9]+$ ]] || return 1
    now="$(date +%s)"
    (( now - lastTime < notifyInterval ))
}

remember_notification() {
    local remoteCommit="$1"

    mkdir -p "$stateDir" || return 0
    {
        printf '%s\n' "$remoteCommit"
        date +%s
    } > "$notifyState" 2> /dev/null || true
}

send_update_notification() {
    local remoteCommit="$1"

    notify-send \
        "I38 update available" \
        "A newer I38 version is available. Update your checkout, then run i38.sh -u or rerun i38.sh to refresh your setup." \
        2> /dev/null || return 1
    remember_notification "$remoteCommit"
}

stop_update_check() {
    rm -rf "$lockDir"
    exit 0
}

if ! command -v git > /dev/null || ! command -v notify-send > /dev/null; then
    exit 0
fi

if [[ -d "$lockDir" ]]; then
    if [[ -f "${lockDir}/pid" ]]; then
        IFS= read -r existingPid < "${lockDir}/pid" || existingPid=""
        if [[ "$existingPid" =~ ^[0-9]+$ ]] && kill -0 "$existingPid" 2> /dev/null; then
            exit 0
        fi
    fi
    rm -rf "$lockDir"
fi

if ! mkdir "$lockDir" 2> /dev/null; then
    exit 0
fi
printf '%s\n' "$$" > "${lockDir}/pid"
trap 'rm -rf "$lockDir"' EXIT
trap stop_update_check INT TERM

sleep "$initialDelay"

while :; do
    installedCommit="$(read_installed_commit)" || exit 0
    remoteCommit="$(read_remote_commit)"
    remoteStatus=$?

    if [[ $remoteStatus -eq 0 && "$remoteCommit" != "$installedCommit" ]]; then
        if ! already_notified "$remoteCommit"; then
            send_update_notification "$remoteCommit"
            exit 0
        fi
    fi

    sleep "$checkInterval"
done