git-mch

#!/bin/bash

set -e

GIT_COMMON_DIR=$(git rev-parse --git-common-dir)
GIT_WORKTREE_DIR=$(git rev-parse --git-dir)
HELPERS_DIR="$GIT_COMMON_DIR/merge-conflict-helpers"

check_conflict_state() {
    if [ ! -f "$GIT_WORKTREE_DIR/MERGE_HEAD" ] && [ ! -f "$GIT_WORKTREE_DIR/REBASE_HEAD" ]; then
        echo "Not in a merge or rebase conflict state."
        exit 1
    fi
}

start_helper() {
    local name="$1"
    if [ -z "$name" ]; then
        echo "Usage: $0 start <name>"
        exit 1
    fi
    check_conflict_state
    local orig_dir="$HELPERS_DIR/$name/orig"
    # Get conflicted files
    git status --porcelain | grep '^UU\|^AA\|^DD' | awk '{print $2}' | while read -r file; do
        # Copy preserving directory
        mkdir -p "$orig_dir/$(dirname "$file")"
        cp "$file" "$orig_dir/$file"
    done
    echo "Started conflict helper for $name"
}

save_helper() {
    local name="$1"
    if [ -z "$name" ]; then
        echo "Usage: $0 save <name>"
        exit 1
    fi
    local orig_dir="$HELPERS_DIR/$name/orig"
    mkdir -p "$orig_dir"
    local diff_file="$HELPERS_DIR/$name/diff.patch"
    if [ ! -d "$orig_dir" ]; then
        echo "No orig directory for $name"
        exit 1
    fi
    # Clear diff file
    > "$diff_file"
    find "$orig_dir" -type f | while read -r orig_file; do
        local rel_file="${orig_file#$orig_dir/}"
        if [ -f "$rel_file" ]; then
            # Create diff
            diff -u "$orig_file" "$rel_file" | removal-of-hashes-from-diff-3-hunks >> "$diff_file" || true
        fi
    done
    echo "Saved diff for $name"
}

removal-of-hashes-from-diff-3-hunks() {
    sed -E 's#^-[|][|][|][|][|][|][|] [a-f0-9]+$#-|||||||#g'
}

apply_helper() {
    local name="$1"
    if [ -z "$name" ]; then
        echo "Usage: $0 apply <name>"
        exit 1
    fi
    local diff_file="$HELPERS_DIR/$name/diff.patch"
    if [ ! -f "$diff_file" ]; then
        echo "No diff file for $name"
        exit 1
    fi
    echo "Applying $diff_file"
    cat "$diff_file" | removal-of-hashes-from-diff-3-hunks | patch -p0
    echo "Applied diff for $name"
}

list_helper() {
    local i

    for i in $HELPERS_DIR/*/diff.patch; do
        date=$(stat "$i" | grep Modify | cut -c9-18)
        i=${i#"$HELPERS_DIR"/}
        i=${i%/diff.patch}
        echo "${date}  ${i}"
    done
}


main() {
    case "$1" in
        start)
            start_helper "$2"
            ;;
        save)
            save_helper "$2"
            ;;
        apply)
            apply_helper "$2"
            ;;
        list)
            list_helper "$2"
            ;;
        *)
            echo "Usage: $0 {start|save|apply} <name>"
            exit 1
            ;;
    esac
}

main "$@"