#!/bin/bash

# Create a dedicated systemd config
#
# usage: ynh_add_systemd_config [--service=service] [--template=template]
# usage: ynh_add_systemd_config [--service=service] [--template=template]  [--others_var="list of others variables to replace"]
# | arg: -s, --service=     - Service name (optionnal, $app by default)
# | arg: -t, --template=    - Name of template file (optionnal, this is 'systemd' by default, meaning ./conf/systemd.service will be used as template)
# | arg: -v, --others_var=  - List of others variables to replace separated by a space. For example: 'var_1 var_2 ...'
#
# This will use the template ../conf/<templatename>.service
# to generate a systemd config, by replacing the following keywords
# with global variables that should be defined before calling
# this helper :
#
#   __APP__       by  $app
#   __FINALPATH__ by  $final_path
#
# And dynamic variables (from the last example) :
#   __VAR_1__    by $var_1
#   __VAR_2__    by $var_2
#
# Requires YunoHost version 2.7.11 or higher.
ynh_add_systemd_config () {
    # Declare an array to define the options of this helper.
    local legacy_args=stv
    local -A args_array=( [s]=service= [t]=template= [v]=others_var= )
    local service
    local template
    local others_var
    # Manage arguments with getopts
    ynh_handle_getopts_args "$@"
    local service="${service:-$app}"
    local template="${template:-systemd.service}"
    others_var="${others_var:-}"

    finalsystemdconf="/etc/systemd/system/$service.service"
    ynh_backup_if_checksum_is_different --file="$finalsystemdconf"
    cp ../conf/$template "$finalsystemdconf"

    # To avoid a break by set -u, use a void substitution ${var:-}. If the variable is not set, it's simply set with an empty variable.
    # Substitute in a nginx config file only if the variable is not empty
    if [ -n "${final_path:-}" ]; then
        ynh_replace_string --match_string="__FINALPATH__" --replace_string="$final_path" --target_file="$finalsystemdconf"
    fi
    if [ -n "${app:-}" ]; then
        ynh_replace_string --match_string="__APP__" --replace_string="$app" --target_file="$finalsystemdconf"
    fi

    # Replace all other variables given as arguments
    for var_to_replace in $others_var
    do
        # ${var_to_replace^^} make the content of the variable on upper-cases
        # ${!var_to_replace} get the content of the variable named $var_to_replace 
        ynh_replace_string --match_string="__${var_to_replace^^}__" --replace_string="${!var_to_replace}" --target_file="$finalsystemdconf"
    done

    ynh_store_file_checksum --file="$finalsystemdconf"

    chown root: "$finalsystemdconf"
    systemctl enable $service --quiet
    systemctl daemon-reload
}

# Remove the dedicated systemd config
#
# usage: ynh_remove_systemd_config [--service=service]
# | arg: -s, --service=     - Service name (optionnal, $app by default)
#
# Requires YunoHost version 2.7.2 or higher.
ynh_remove_systemd_config () {
    # Declare an array to define the options of this helper.
    local legacy_args=s
    local -A args_array=( [s]=service= )
    local service
    # Manage arguments with getopts
    ynh_handle_getopts_args "$@"
    local service="${service:-$app}"

    local finalsystemdconf="/etc/systemd/system/$service.service"
    if [ -e "$finalsystemdconf" ]
    then
        ynh_systemd_action --service_name=$service --action=stop
        systemctl disable $service --quiet
        ynh_secure_remove --file="$finalsystemdconf"
        systemctl daemon-reload
    fi
}

# Start (or other actions) a service,  print a log in case of failure and optionnaly wait until the service is completely started
#
# usage: ynh_systemd_action [--service_name=service_name] [--action=action] [ [--line_match="line to match"] [--log_path=log_path] [--timeout=300] [--length=20] ]
# | arg: -n, --service_name= - Name of the service to start. Default : $app
# | arg: -a, --action=       - Action to perform with systemctl. Default: start
# | arg: -l, --line_match=   - Line to match - The line to find in the log to attest the service have finished to boot. If not defined it don't wait until the service is completely started. WARNING: When using --line_match, you should always add `ynh_clean_check_starting` into your `ynh_clean_setup` at the beginning of the script. Otherwise, tail will not stop in case of failure of the script. The script will then hang forever.
# | arg: -p, --log_path=     - Log file - Path to the log file. Default : /var/log/$app/$app.log
# | arg: -t, --timeout=      - Timeout - The maximum time to wait before ending the watching. Default : 300 seconds.
# | arg: -e, --length=       - Length of the error log : Default : 20
#
# Requires YunoHost version 3.5.0 or higher.
ynh_systemd_action() {
    # Declare an array to define the options of this helper.
    local legacy_args=nalpte
    local -A args_array=( [n]=service_name= [a]=action= [l]=line_match= [p]=log_path= [t]=timeout= [e]=length= )
    local service_name
    local action
    local line_match
    local length
    local log_path
    local timeout
    # Manage arguments with getopts
    ynh_handle_getopts_args "$@"
    service_name="${service_name:-$app}"
    action=${action:-start}
    line_match=${line_match:-}
    length=${length:-20}
    log_path="${log_path:-/var/log/$service_name/$service_name.log}"
    timeout=${timeout:-300}

    # Start to read the log
    if [[ -n "$line_match" ]]
    then
        local templog="$(mktemp)"
        # Following the starting of the app in its log
        if [ "$log_path" == "systemd" ]
        then
            # Read the systemd journal
            journalctl --unit=$service_name --follow --since=-0 --quiet > "$templog" &
            # Get the PID of the journalctl command
            local pid_tail=$!
        else
            # Read the specified log file
            tail --follow=name --retry --lines=0 "$log_path" > "$templog" 2>&1 &
            # Get the PID of the tail command
            local pid_tail=$!
        fi
    fi

    # Use reload-or-restart instead of reload. So it wouldn't fail if the service isn't running.
    if [ "$action" == "reload" ]; then
        action="reload-or-restart"
    fi

    # If the service fails to perform the action
    if ! systemctl $action $service_name
    then
        # Show syslog for this service
        ynh_exec_err journalctl --quiet --no-hostname --no-pager --lines=$length --unit=$service_name
        # If a log is specified for this service, show also the content of this log
        if [ -e "$log_path" ]
        then
            ynh_print_err --message="--"
            ynh_exec_err tail --lines=$length "$log_path"
        fi
        # Fail the app script, since the service failed.
        ynh_die
    fi

    # Start the timeout and try to find line_match
    if [[ -n "${line_match:-}" ]]
    then
        local i=0
        for i in $(seq 1 $timeout)
        do
            # Read the log until the sentence is found, that means the app finished to start. Or run until the timeout
            if grep --extended-regexp --quiet "$line_match" "$templog"
            then
                ynh_print_info --message="The service $service_name has correctly executed the action ${action}."
                break
            fi
            if [ $i -eq 3 ]; then
                echo -n "Please wait, the service $service_name is ${action}ing" >&2
            fi
            if [ $i -ge 3 ]; then
                echo -n "." >&2
            fi
            sleep 1
        done
        if [ $i -ge 3 ]; then
            echo "" >&2
        fi
        if [ $i -eq $timeout ]
        then
            ynh_print_warn --message="The service $service_name didn't fully executed the action ${action} before the timeout."
            ynh_print_warn --message="Please find here an extract of the end of the log of the service $service_name:"
            ynh_exec_warn journalctl --quiet --no-hostname --no-pager --lines=$length --unit=$service_name
            if [ -e "$log_path" ]
            then
                ynh_print_warn --message="\-\-\-"
                ynh_exec_warn tail --lines=$length "$log_path"
            fi
        fi
        ynh_clean_check_starting
    fi
}

# Clean temporary process and file used by ynh_check_starting
# (usually used in ynh_clean_setup scripts)
#
# usage: ynh_clean_check_starting
#
# Requires YunoHost version 3.5.0 or higher.
ynh_clean_check_starting () {
    if [ -n "$pid_tail" ]
    then
        # Stop the execution of tail.
        kill -SIGTERM $pid_tail 2>&1
    fi
    if [ -n "$templog" ]
    then
        ynh_secure_remove "$templog" 2>&1
    fi
}