#!/bin/bash
#
# cobrand-checks: Check for template changes in a version upgrade

set -e

# Read in command line arguments

POSITIONAL=()
while [[ $# -gt 0 ]]
do
key="$1"
case $key in
    -h|--help)
    HELP=yes
    shift # past argument
    ;;
    -l|--list)
    LIST=yes
    shift # past argument
    ;;
    -d|--diff)
    DIFF=yes
    shift # past argument
    ;;
    -i|--interactive)
    INTERACTIVE=yes
    shift # past argument
    ;;
    *)    # unknown option
    POSITIONAL+=("$1") # save it in an array for later
    shift # past argument
    ;;
esac
done
set -- "${POSITIONAL[@]}" # restore positional parameters

# Parse command line arguments or work out defaults

function help {
    cat <<END
cobrand-checks COBRAND [OLD-REVISION] [NEW-REVISION]

If OLD/NEW revisions are not specified, OLD defaults to the most recent tag
accessible from the current checkout, and NEW defaults to either the most
recent tag at all, or HEAD if HEAD is a descendant of the most recent tag at
all.

With no long argument, acts as if --list is given.

    --list          List templates present in COBRAND that have changed in core
                    between REVISIONs
    --diff          Show diff of those files
    --interactive   Step through the files one by one, showing diffs and editing
    --help          Print usage message and exit
END
}

if [ "$HELP" ]; then
    help
    exit 0
fi

COBRAND=$1

if [ -z "$COBRAND" ]; then
    echo "Please provide a cobrand"
    echo
    help
    exit 1
fi

if [ -z "$LIST" -a -z "$DIFF" -a -z "$INTERACTIVE" ]; then
    LIST=yes
fi

CURRENT_COMMIT=$(git rev-parse --verify --short --abbrev-ref HEAD)
MOST_RECENT_CHECKED_OUT_TAG=$(git describe --abbrev=0 --tags)
MOST_RECENT_TAG_AT_ALL=$(git describe --tags $(git rev-list --tags --max-count=1))

OLD_REV=${2:-$MOST_RECENT_CHECKED_OUT_TAG}
if [[ "$MOST_RECENT_TAG_AT_ALL" == "$MOST_RECENT_CHECKED_OUT_TAG" ]]; then
    NEW_REV=${3:-$CURRENT_COMMIT}
else
    NEW_REV=${3:-$MOST_RECENT_TAG_AT_ALL}
fi

# Work out which templates are relevant

CORE_TEMPLATE_CHANGES=$(git diff --name-only $OLD_REV..$NEW_REV templates/web/base | sort)
COBRAND_TEMPLATES=$(find "templates/web/$COBRAND" -type f \! -name *.ttc | sed "s/$COBRAND/base/" | sort)

CHANGED_FILES=$(comm -12 <(echo "$CORE_TEMPLATE_CHANGES") <(echo "$COBRAND_TEMPLATES"))

if [ "$LIST" ]; then
    if [ "$CHANGED_FILES" ]; then
        echo "$CHANGED_FILES"
    fi
    exit 0
fi

if [ "$DIFF" ]; then
    if [ "$CHANGED_FILES" ]; then
        git diff --color $OLD_REV..$NEW_REV $CHANGED_FILES
    fi
    exit 0
fi

# --interactive from here

function title {
    printf "\033c"
    TITLE="Comparing $OLD_REV to $NEW_REV"
    echo $TITLE
    printf '=%.0s' $(seq 1 ${#TITLE})
    echo
    echo $i
    printf '~%.0s' $(seq 1 ${#i})
    echo
    echo
}

function prompt {
    cat <<END

Pick what to do:
0) Compare base $OLD_REV..$NEW_REV
1) Compare $OLD_REV:base to HEAD:$COBRAND
2) Compare $NEW_REV:base to HEAD:$COBRAND
e) Edit $j with vimdiff (:qa to exit)
n) Next
q) Quit
END
}

(
for i in $CHANGED_FILES; do
    title
    echo "$(git diff --color $OLD_REV..$NEW_REV $i)" # Avoid pager woes
    j=${i/base/$COBRAND}
    prompt
    while true; do
        read -n1 -s -r key
        if [ "$key" = '0' ]; then
            title
            echo "$(git diff --color $OLD_REV..$NEW_REV $i)"
            prompt
        elif [ "$key" = '1' ]; then
            title
            diff -u <(git show $OLD_REV:$i) $j || true
            prompt
        elif [ "$key" = '2' ]; then
            title
            diff -u <(git show $NEW_REV:$i) $j || true
            prompt
        elif [ "$key" = 'e' -o "$key" = 'E' ]; then
            vim -d <(git show $NEW_REV:$i) $j
        elif [ "$key" = 'n' -o "$key" = 'N' ]; then
            break;
        elif [ "$key" = 'q' -o "$key" = 'Q' ]; then
            exit;
        fi
    done
done
)