#!/bin/bash

set -x
fifo=""

GIT_SSL_NO_VERIFY=true

init_fifo () {
    trap "rm -f $fifo" EXIT
    if [ $? -eq 0 ]; then
        # set trap
        if [[ ! -p "$fifo" ]]; then
            mkfifo "$fifo"
            if [ $? -eq 0 ]; then
                # fifo created
                echo "created fifo=$fifo"
                return 0
            fi
        fi
    fi
    return 1
}

read_config() {
    fifo_dir=$(cat "$1" | jq -r .fifo_dir)
    if [ -z "$fifo_dir" ]; then
        return 1 
    fi

    fifo=$(cat "$1" | jq -r .fifo)
    if [ -z "$fifo" ]; then 
        return 1
    fi
    
    fifo="${fifo_dir}/$fifo"
    return 0
}

wait_for_trigger() {
    if [[ "$1" -eq -1 ]]; then
        # wait for external impulse
        if read line <$fifo; then
            if [ "$line" = "quit" ] || [ "$line" = "update" ]; then
                echo "$line"
            fi
        fi
    else
        sleep $1
        echo "sleep"
    fi
}

# APISM has al least two TCP-ports open: 7778 and 7779. To check for a running
# APISM it is therefore enough to check for the port 7778. netcat will return 0
# if the port 7778 is open.
check_for_apism() {
    return 0

    nc localhost 7778
    if [ $? -eq 0 ]; then
    	return 0
    fi
    return 1
}

######################### send_to_ismas.txt ###################################
#   #M=GH_APP
#   #C=REQ_ISMASParameter
#   #J={}
#   {
#       "DEV_ID": {
#           "Device_Type": "2020",
#           "Custom_ID": 999,
#           "Device_ID": 1
#       },
#       "REQ_ISMASParameter_#1": {}
#   }
#
# APISM should respond with (something like this):
#
#   {
#       "REQ_ISMASPARAMETER#69553_Response": {
#           "Aknoledge": "OK"
#       },
#       "Dev_ID": {
#           "Device_Type": "ISMAS",
#           "Custom_ID": 999,
#           "Device_ID": 2
#       },
#       "Fileupload": [
#           { "IPK": "BladiBlupp.Zip",
#             "MD5": "01234567890123456789012345678901"}
#       ],
#       "Parameter": {
#           "Location": "An der Bahn 11",
#           "Group": "G1",
#           "Zone": "Z1",
#           "Name": "Bruno",
#           "SecNumber": "0",
#           "LastAcc": "1",
#           "GPSLat": "49,6019",
#           "GPSLon": "12,1258"
#       }
#   }
#
# where the interesting part is contained in "FileUpload".
# 
check_for_updates() {
    # ismas_response=$(cat send_to_ismas.txt; sleep 1) | nc localhost 7778)
    return 0
}

backup_previous_version() {
    return 0
}

fetch_updates() {
    return 0
}

check_updates() {
    return 0
}

revert_updates() {
    return 0
}

lock_before_installing_updates() {
    return 0
}

do_update_dry_run() {
    return 0
}

do_update() {
    return 0
}

fallback_to_previous_version() {
    return 0;
}

unlock_after_installing_updates() {
    return 0;
}

cleanup_previous_version() {
    return 0
}

send_reboot_message_to_system_controller() {
    return 0
}

###############################################################################
#                                                                             
#                            UPDATE CONTROLLER
#                                                                           
###############################################################################
UpdateController() {
    local trigger_reboot=false
    local check_apism_count=0
    local try_update_count=0
    local try_lock_count=0
    local try_unlock_count=0
    local trigger_timeout=-1

    # read config parameters
    # read_config

    # By default (trigger_timeout==-1), UpdateController can only be triggered
    # from some external source to perform an update.
    while :
    do
        trigger=$(wait_for_trigger $trigger_timeout)
        echo "trigger=$trigger"
        if [ "$trigger" = "quit" ]; then
            $trigger_reboot = true
        elif [ "$trigger" != "update" ]; then
            continue
        fi

        if $trigger_reboot; then
            echo "CRITICAL send message to reboot the PSA"
            send_reboot_message_to_system_controller
            continue
        fi

        # Is APISM running, listening on the correct ports etc. ?
        while :
        do
            if ! check_for_apism; then
                var=$((var+1))
                check_apism_count=$((check_apism_count+1))
                if [[ "$check_apism_count" -eq 5 ]]; then
                    trigger_reboot=true
                    check_apism_count=0
                    echo "ERROR APISM not working"
                    continue 2
                fi
                echo "[$check_apism_count]: $(date +'%Y-%m-%d %T') check APISM"
                sleep 60s
            else
                # APISM up and working
                check_apism_count=0
                break
            fi
        done

        echo "$(date +'%Y-%m-%d %T') checking for updates..."
        exit 1
       
        # Are there new updates available ?
        if ! check_for_updates; then
            echo "DEBUG no updates available"
            continue
        fi
        
        echo "$(date +'%Y-%m-%d %T') fetching updates..."
        exit 1
       
        # Fetch new updates (using git)
        while :
        do
            if ! fetch_updates; then
                try_updates_count=$((try_updates_count+1))
                if [[ "$try_updates_count" -eq 5 ]]; then
                    trigger_reboot=true
                    echo "ERROR fetching updates"
                    continue 2
                fi
                sleep 60s
            else
                # Fetched updates successfully 
                try_updates_count=0
                break
            fi
        done

        # Check the updates for:
        #   * correct MD5
        #   * compatibility with PSA
        #   ...
        if ! check_updates; then
            echo "ERROR check_updates"
            revert_updates
            trigger_reboot=true
            continue
        fi
       
        # perform a dry-run and check if everything might work as expected. 
        if ! do_update_dry_run; then
            echo "ERROR do_update_dry_run"
            revert_updates
            trigger_reboot=true
            continue
        fi
        
        # Backup before any updates in case some previous test was wrong
        if ! backup_previous_version; then
            echo "ERROR backup_previous_version"
            revert_updates
            trigger_reboot=true
            continue
        fi

        # Lock the PSA so all other tasks on the PSA are in sync with the update
        while :
        do
            if ! lock_before_installing_updates; then
                try_lock_count=$((try_lock_count+1))
                if [[ "$try_lock_count" -eq 5 ]]; then
                    revert_updates
                    fallback_to_previous_version
                    trigger_reboot=true
                    echo "ERROR locking PSA"
                    continue 2
                fi
                sleep 60s
            else 
                # Locked PSA successfully
                try_lock_count=0
                break
            fi
        done

        # Actually do the update
        if ! do_update; then
            echo "ERROR do_update"
            revert_updates
            fallback_to_previous_version
            trigger_reboot=true
            continue
        fi

        while :
        do
            # If all went well, the PSA can return to normal operation
            if ! unlock_after_installing_updates; then
                try_unlock_count=$((try_unlock_count+1))
                if [[ "$try_unlock_count" -eq 5 ]]; then
                    revert_updates
                    fallback_to_previous_version
                    trigger_reboot=true
                    echo "ERROR unlocking PSA"
                    continue 2
                fi
                sleep 60s
            else 
                # Unlocked PSA successfully
                try_unlock_count=0
                break
            fi
        done

        # Cleanup.
        if ! cleanup_previous_version; then
            echo "ERROR cleanup_previous_version"
        fi
    done
}

###############################################################################

if [ $# -ne 1 ] ; then
    echo "Usage: $0 filename"  
    exit 1 
else
    if read_config "$1" ; then
        init_fifo
        UpdateController
    fi
fi