git-split-commit

#!/bin/bash

SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )

set -e

RESET=0

function log() {
    echo "$1" > /dev/stderr
}

function usage() {
    log "Usage: $0 [--reset]"
    log ""
    log "  --reset: instead of reverting HEAD, discard it."
    log ""
}

while [[ $# -gt 0 ]]; do
    case $1 in
        --help)
            usage
            shift
            exit 0
            ;;
        --reset)
            RESET=1
            shift
            ;;
        *)
            echo "Unknown option $1"
            log ""
            usage
            exit 1
            ;;
    esac
done

if ! git diff --exit-code >& /dev/null; then
    log "git diff did not give an empty output, exiting."
    exit 1
fi

COMMIT="$(git rev-parse HEAD)"

# Create patch for HEAD
BASE_PATCH="$(git format-patch HEAD^)"

# Split the patch
PATCHES_LIST_FILE="patches-list.txt"
"$SCRIPT_DIR/split-patch.py" --patches-list "$PATCHES_LIST_FILE" "$BASE_PATCH"

# Get the list of patches
if test -e "$PATCHES_LIST_FILE"; then
    if test "$RESET" -eq 1; then
        # Discard the original commit
        git reset --hard HEAD^
    else
        # Revert original commit
        git revert --no-edit "$COMMIT"
    fi

    # If something is left, recreate the base commit
    if test -s "$BASE_PATCH"; then
        git apply --index "$BASE_PATCH"
        git commit -C "$COMMIT"
    fi

    PATCHES="$(cat $PATCHES_LIST_FILE)"

    # Create one commit per-patch
    for PATCH in $PATCHES; do
        git apply --index "$PATCH"
        git commit -m"$PATCH"
    done

    # Get rid of all the generated patches
    rm $PATCHES "$PATCHES_LIST_FILE"
fi

# Drop the original patch
rm "$BASE_PATCH"