#!/bin/bash

src=$(realpath $(dirname $BASH_SOURCE)/../../)
base=$src/libraries
declare -A header_dirs

arg_verbose=false
arg_create_commits=false

usage(){
    cat <<EOF
Usage: $(basename $BASH_SOURCE) [-h|--help]

Fix includes of libraries headers in source files to be as the following:

 - If the header is in the same directory the source belongs to, then the
 notation #include "" is used with the path relative to the directory
 containing the source.

 - If the header is outside the directory containing the source, then we use
 the notation #include <> with the path relative to libraries folder.

The output is a log of the process.

Options:
    -h,--help
        Display this help message.

    -v,--verbose
        Not only log errors and warnings but also substitutions.

    -c,--create-commits
        Create commits in the end.

    --commit
        Assume that the user have run the substitutions beforehand - only
        create the commits.
EOF
}

create_commits(){
    for f in $(git diff-files --name-only); do
        if [[ ${f%%/*} == "libraries" ]]; then
            echo $f | sed "s,\(libraries/[^/]*\)/.*,\1,"
        else
            echo ${f%%/*}
        fi
    done | uniq | while read d; do
        if [[ $d == libraries/* ]]; then
            commit_base=${d#libraries/}
        else
            commit_base=$d
        fi
        cat >/tmp/commit_msg <<EOF
$commit_base: standardize inclusion of libaries headers

This commit changes the way libraries headers are included in source files:

 - If the header is in the same directory the source belongs to, so the
 notation '#include ""' is used with the path relative to the directory
 containing the source.

 - If the header is outside the directory containing the source, then we use
 the notation '#include <>' with the path relative to libraries folder.

Some of the advantages of such approach:

 - Only one search path for libraries headers.

 - OSs like Windows may have a better lookup time.
EOF
        git add -u $d
        git commit -F /tmp/commit_msg
    done
}

replace_include(){
    local file=$1
    local n=$2
    local new_path=$3
    local old_path=$4
    local regex="\(#\s*include\s*\)[<\"].\+[>\"]"

    [[ $new_path == $old_path ]] && return

    $arg_verbose && echo "$file:$n: $old_path -->  $new_path"
    if ! sed -i "${n}s,$regex,\1$new_path," $file; then
        echo Error on executing command: sed -i "${n}s,$regex,\1$new_path," $file >&2
        kill -SIGINT $$
    fi
}

fix_includes(){
    local file=$1
    local header=$2
    local dirs=(${header_dirs[$header]})
    local num_dirs=${#dirs[@]}
    local regex="^\s*#\s*include\s*[<\"]\(.*/\)\?$header[>\"]"

    grep -ahno $regex $file | while IFS=":" read n match; do
        path=$(echo $match | sed "s/^\s*#\s*include\s*//g")
        delim=${path:0:1}
        path=${path:1:(${#path}-2)}
        file_dir=$(realpath $(dirname $file))

        if [[ $delim == "\"" ]]; then
            localpath=$file_dir/$path
            if [[ -f $localpath ]]; then
                # verify if file is under to the file dir
                localpath=$(realpath $localpath)
                [[ $localpath == $file_dir* ]] && continue

                # if not under file dir, check if $localpath is under $base
                if [[ $localpath == $base* ]]; then
                    new_path=${localpath#$base/}
                    replace_include $file $n \<$new_path\> \"$path\"
                    continue
                fi
            fi
        fi

        match_count=0
        possible_paths=()
        for dir in "${dirs[@]}"; do
            if [[ $dir/$header == *$path ]]; then
                ((match_count++))
                new_path=$dir/$header
                possible_paths[${#possible_paths[@]}]=$new_path
            fi
        done

        if [[ $match_count -eq 0 ]]; then
            echo "$file:$n: couldn't find a match for inclusion of $path"
        elif [[ $match_count -eq 1 ]]; then
            # check if included header is under file dir
            if [[ -f $file_dir/$path ]]; then
                new_path=\"$(realpath $file_dir/$path --relative-to $file_dir)\"
            else
                new_path=\<$new_path\>
            fi
            if [[ $delim == '"' ]]; then path=\"$path\"; else path=\<$path\>; fi
            replace_include $file $n $new_path $path
        else
            echo "$file:$n: more than one match for inclusion of $path"
            echo "    possible paths:"
            for p in "${possible_paths[@]}"; do
                echo "    $p"
            done
        fi
    done
}

trap_reset_tree(){
    echo
    echo Process killed or interrupted! Reseting tree...
    git -C $src reset --hard
    exit 1
}

# parse args
while [[ -n $1 ]]; do
    case "$1" in
    -h|--help)
        usage
        exit 0
        ;;
    -v|--verbose)
        arg_verbose=true
        ;;
    -c|--create-commits)
        arg_create_commits=true
        ;;
    --commit)
        create_commits
        exit $?
        ;;
    *)
        usage >&2
        exit 1
        ;;
    esac
    shift
done

trap trap_reset_tree SIGINT SIGKILL

if ! git -C $src diff-files --quiet --exit-code; then
    echo You have unstaged changes, please commit or stash them beforehand >&2
    exit 1
fi

pushd $src > /dev/null

# collect all headers
git -C $base ls-files *.h > /tmp/headers
total=$(cat /tmp/headers | wc -l)
header_max_len=0
while read f; do
    header=$(basename $f)
    dir=$(dirname $f)
    if [[ -z ${header_dirs[$header]} ]]; then
        header_dirs[$header]=$dir
    else
        header_dirs[$header]+=" $dir"
    fi
    printf "\rCollecting header files paths... $((++i))/$total" >&2
    [[ ${#header} -gt $header_max_len ]] && header_max_len=${#header}
done </tmp/headers
echo

total=${#header_dirs[@]}
i=0
for header in "${!header_dirs[@]}"; do
    regex="#\s*include\s*[<\"]\(.*/\)\?$header[>\"]"
    printf "\r($((++i))/$total) Fixing includes for header %-${header_max_len}s" $header >&2

    # for each file that includes $header
    git grep -l $regex | while read f; do
        fix_includes $f $header
    done
done

$arg_create_commits && create_commits

popd > /dev/null