#!/bin/bash
# enter
#
# Using this tool, we can seek a whole zchain, if available from
# an IPFS CID or an IPNS link.
#
# Default (no arguments) will retrieve the local ZCHAIN starting
# from the IPFS CID stored in the file that is tracked by the
# $AK_ZLATEST environment variable.
#
# enter [-n IPNS_LINK]
# enter [IPFS CID]
# enter -nV
# enter
#
# Returns a JSON array representing the chain retrieved.
# Logs messages to $LOGSFILE.

PROGRAM="$(basename $0)"

logit(){
    ak-logthis "<$PROGRAM>" "$1" "$2"
}

usage(){
    echo "$PROGRAM - Crawl an arching kaos chain"
    echo "-----------------------------------"
    echo "Usage:"
    echo "    --help, -h                             Print this help and exit"
    echo "    --chain <ipns-link>, -n <ipns-link>    Crawl specified chain"
    echo "    --no-verify, -nV                       Don't verify signatures"
    echo "    <ipfs-link>                            Specify IPFS CID for entrance"
    echo ""
    echo "Note that combined flags don't work for now"
    echo "Running with no flags crawls your chain based on AK_ZLATEST environment variable"
}
# Start of tests
#entrance="QmW5WVXCJfhb4peHG6cbEdamC24vZzMX2Vz386vpENh38U"
#entrance="QmNjQq7GkuXGF8kFT1z2Mv3i4JhY7sBXVUmHDiR1zkQjoE"
#entrance="QmbFMke1KXqnYyBBWxB74N4c5SBnJMVAiMNRcGu6x1AwQH"
# End of tests
verify=1
if [ ! -z "$1" ] && [ "$1" == "-h" ] || [ "$1" == "--help" ]
then
    usage
    exit
elif [ ! -z "$1" ] && [ "$1" == "-nV" ] || [ "$1" == "--no-verify" ]
then
    verify=0
    entrance="$(cat $AK_ZLATEST)"
elif [ ! -z "$1" ] && [ "$1" == "-n" ]
then
    entrance="$(ak-ipns-resolve $2)"
elif [ ! -z "$1" ]
then
    echo $1 | grep -e 'Qm.\{44\}' >/dev/null
    if [ "$?" -ne 0 ]
    then
        logit "[ERROR]" "Argument provided was not an IPFS CIDv0 string"
        exit 1
    fi
    entrance="$1"
else
    # By default we enter from the latest block
    # We can alter this by changing this value
    entrance="$(cat $AK_ZLATEST)"
fi
# We assign the IPFS CIDv0 of an empty file as this is used
# as our GENESIS block, hence the "seed" that the tree grows
# from.
seed="$(cat $AK_ZGENESIS)"

# We assume that we found the entrance inside a block, hence
# ZBLOCK is labeled as previous
zblock="$entrance"

# Enter temp folder
TEMPASSIN="/tmp/aktmp_$(date -u +%s)"
mkdir $TEMPASSIN
cd $TEMPASSIN
counter=0
# The loop
# We break the loop from inside the loop
while true
do
    if [ $counter == 0 ]
    then
        echo -n '['
    fi
    counter=$(expr $counter + 1)
    # Check if $zblock exists as variable
    if [ ! -v $zblock ]
    then
        # Check if it is not our seed cause if it is we skip this part
        if [ "$zblock" != "$seed" ]
        then
            # Reset timestamp since it's introduced later
            timestamp=''
            # Announce to logs which ZBLOCK is being read at the moment
            logit "[INFO]" "Examining $zblock"
            echo -n '{"zblock":"'$zblock'",'

            # We concatenate the zblock's contents, pipe
            # them through filter ak-json2bash and output
            # them to tmp-file
            # 
            # We check if any $zblock at all
            ipfs --timeout=10s cat $zblock > /dev/null 2>&1
            if [ "$?" -ne 0 ]
            then
                logit "[ERROR]" "ZBLOCK $zblock READ failed"
                exit 1
            fi
            logit "[INFO]" "ZBLOCK $zblock READ"
  
            # If it's JSON formated
            ipfs --timeout=10s cat $zblock | jq -M > /dev/null 2>&1
            if [ "$?" -ne 0 ]
            then
                logit "[ERROR]" "ZBLOCK $zblock is not JSON"
                exit 1
            fi
            logit "[INFO]" "ZBLOCK $zblock is JSON"

            # Then we pass it through the filter and save it
            ipfs --timeout=10s cat $zblock | ak-json2bash > $TEMPASSIN/tmp-zblock

            # Be sure that there are the expected values
            # We need 'block' and 'block_signature' inside a 'zblock'
            # Exit if any is missing
            grep -e 'block_signature' $TEMPASSIN/tmp-zblock > /dev/null 2>&1
            if [ "$?" -ne 0 ]
            then
                logit "[ERROR]" "ZBLOCK $zblock doesn't contain a block_signature"
                exit 1
            fi
            logit "[INFO]" "ZBLOCK $zblock contains a block_signature"

            grep -e 'block=' $TEMPASSIN/tmp-zblock > /dev/null 2>&1
            if [ "$?" -ne 0 ]
            then
                logit "[ERROR]" "ZBLOCK $zblock has no block"
                exit 1
            fi
            logit "[INFO]" "ZBLOCK $zblock has block"

            # We create files named after each ZBLOCK IPFS CID for later
            # reference. Files are empty.
            touch $ZBLOCKDIR/$zblock
            logit "[INFO]" "Created reference"

            # Supposingly you are on a safe environment and you only have
            # access to your chain, I would consider mild secure to source
            # the files into your bash.
            # File an issue/pull request if you think it can be done better!!
            source $TEMPASSIN/tmp-zblock
            logit "[INFO]" "ZBLOCK SOURCED"

            # Same as above applies to BLOCK and DATA subparts of each ZBLOCK
            # BLOCKS
            echo -n '"block":"'$block'",'
            ipfs --timeout=10s cat $block | ak-json2bash > $TEMPASSIN/tmp-block
            if [ "$?" -ne 0 ]
            then
                logit "[ERROR]" "BLOCK $block READ failed"
                exit 1
            fi

            grep -e 'timestamp' -e 'gpg' -e 'data' -e 'action' -e 'detach' -e 'previous' $TEMPASSIN/tmp-block > /dev/null 2>&1
            if [ "$?" -ne 0 ]
            then
                logit "[ERROR]" "BLOCK $block is NOT a valid block"
                exit 1
            fi
            logit "[INFO]" "BLOCK $block is a block"

            source $TEMPASSIN/tmp-block
            logit "[INFO]" "BLOCK $block SOURCED"
            touch $BLOCKDIR/$block
            logit "[INFO]" "BLOCK REFERENCED"
            module="$(echo $action | sed -e 's/\// /g' | awk '{ print $1 }')"
            logit "[INFO]" "DATA is $module module."
            command="$(echo $action | sed -e 's/\// /g' | awk '{ print $2 }')"
            logit "[INFO]" "COMMAND is $command"
            if [ ! -v $timestamp ]
            then
                echo -n '"timestamp":"'$timestamp'",'
            fi
            echo -n '"block_signature":"'$block_signature'",'
            echo -n '"detach":"'$detach'",'
            echo -n '"module":"'$module'",'
            echo -n '"action":"'$command'",'
            echo -n '"gpg":"'$gpg'",'
            if [ $verify == 1 ]
            then
                ipfs get $gpg > /dev/null 2>&1
                if [ "$?" -ne 0 ]
                then
                    logit "[ERROR]" "Could not get GPG key: $gpg ."
                    exit 1
                fi
                gpg2 --import $gpg > /dev/null 2>&1
                if [ "$?" -ne 0 ]
                then
                    logit "[ERROR]" "Could not import GPG key: $gpg ."
                    exit 1
                fi
                ipfs get $block_signature > /dev/null 2>&1
                if [ "$?" -ne 0 ]
                then
                    logit "[ERROR]" "Error while getting $block_signature for $block"
                    exit 1
                fi
                mv $block_signature $block.asc
                logit "[INFO]" "Block signature downloaded"
                ipfs get $block > /dev/null 2>&1
                if [ "$?" -ne 0 ]
                then
                    logit "[ERROR]" "Could not get $block block"
                    exit 1
                fi
                logit "[INFO]" "Downloaded block $block."
                gpg2 --verify $block.asc > /dev/null 2>&1
                if [ "$?" -ne 0 ]
                then
                    logit "[ERROR]" "Could not verify $block with GPG key $gpg."
                    exit 1
                fi
                logit "[GPG]" "$gpg signature of $block is verified."
            fi
            ak-data-expand $data $gpg

            if [ "$?" -ne 0 ]
            then
                logit "[ERROR]" "Failed on data signature verification [data: $data, gpg: $gpg, zblock: $zblock]"
                exit 1
            fi

            # DATA (but we don't source it's stuff)
            # Only print to stdout
            #ipfs --timeout=10s cat $data
            touch $DATADIR/$data

            # Now, since we sourced the BLOCK to our terminal, we can search
            # for $previous variable. In case we don't find one, we append one
            # and we exit.
            if [ -v $previous ]
            then
                logit "[WARNING]" "Block $block has no previous zblock, appending pseudo genesis to exit gracefully."
                echo -n '"previous":"genesis"},{"genesis":"genesis"}]'
                logit "[INFO]" "Reached pseudo-genesis, counted $counter zblocks."
                exit 0

            # Otherwise, we inform of the sequence
            else
                #echo "$zblock after $previous"
                logit "[INFO]" "Found a previous block for $zblock: $previous"
                echo -n '"previous":"'$previous'"},'
                zblock=$previous
            fi

        # Now check if it is equal to the seed
        # which apparently means we reached the seed.
        elif [ "$zblock" == "$seed" ]
        then
            #echo "$zblock is GENESIS block"
            #echo '"'$zblock'":{ "GENESIS":"GENESIS"}] '
            echo -n '{"genesis":"genesis"}]'
            logit "[INFO]" "Reached $seed, counted $counter zblocks."
            exit 0
        fi
    # And finally, if nothing is there exit with error
    else
        echo "Check not passed... No previous IPFS CID"
        exit 1
    fi
done