#!/bin/bash

############################################################
#  Program: migrate.sh                                     #
############################################################

## BEGIN SCRIPT
usage()
{
    cat << EOF
usage: $(basename $0) [OPTIONS] <COMMAND>

OPTIONS can have:
    -h      Show this message
    -v      Verbose

COMMAND can be one of:
    up
    all

You can either write the db credentials in a file named 'config'
located in the same dir as this script, or pass them like:
user=someuser host=somehost pass=somepass db=somedbname $(basename $0) up.

Also, any variables written in the config file will overwrite those
in the command line.
EOF
}

debug()
{
    [ -z $VERBOSE ] && echo $1
}

EXIT_INVALID_ARGS=1
EXIT_SQL_ERROR=2

VERBOSE=0

# Check options passed in.
while getopts "hv" OPTION
do
    case $OPTION in
        h)
            usage
            exit EXIT_INVALID_ARGS
            ;;
        v)
            VERBOSE=1
            ;;
        ?)
            usage
            exit EXIT_INVALID_ARGS
            ;;
    esac
done

shift $(($OPTIND-1))

# Checks for custom config file path
[ -z "$cfg" ] && cfg="./config"
if [ -e "$cfg" ]
then
    source "$cfg"
fi

# Show usage when we can't find or understand the mandatory parameters.
if [ $# -ne 1 ] \
    || ! (echo $1 | grep -x 'up\|all' &>/dev/null) \
    || [ -z "$user" ] || [ -z "$host" ]
then
    usage
    exit EXIT_INVALID_ARGS
else
    cmd=$1
fi

# If no basedir was informed, use current dir
[ -z "$basedir" ] && basedir=$(pwd)

for sql_file in "$basedir"/db/*.sql
do
    debug "Checking filename format for '$sql_file'"
    # If the filename is not in the format YYYYMMDD-HH:MM:SS_description.sql we skip it
    if (echo $sql_file | grep -x '[0-9]\{8\}-\([0-9]\{2\}:\)\{2\}[0-9]\{2\}_[a-zA-Z0-9_]\+\.sql')
    then
        # If this file exists, we have some previously executed migration
        if [ -e "$basedir"/db/.last_migration ]
        then
            last_migration=$(cat "$basedir"/db/.last_migration)
            current_filename=$(basename "$sql_file")
            # Check if the current $sql_file is newer than the last one
            if [[ $(date -d "$(echo ${last_migration:0:17} | sed 's/-/ /')" +%s) \
                > $(date -d "$(echo ${current_filename:0:17} | sed 's/-/ /')" +%s) ]]
            then
                debug "File '$sql_file' is older than last sucessfully executed file" \
                        "'$(cat $basedir/db/.last_migration). Skipping..."
                continue
            fi
        fi
        debug "Executing SQL file $sql_file"
        # TODO: implement SQL Server branch
        mysql_out=$(mysql -u"$user" -p"$pass" -h"$host" "$db" < $sql_file)
        debug "MySQL exit code: $?"
        if [ $? -ne 0 ]
        then
            debug $mysql_out
            exit $EXIT_SQL_ERROR
        fi
    else
        debug "Filename '$sql_file' cannot be recognized. Skipping..."
        continue
    fi

    echo "$sql_file" > $basedir/db/.last_migration

    if [[ $cmd = "up" ]]
    then
        break
    fi
done

exit 0