#!/usr/bin/env bash

set -e

# Locale can change behavior of utilities like 'sort' but we want the output
# to be stable on all machines.  Force the locale to 'C' for consistency.
export LC_ALL=C

function show_usage {
    cat \
        << EOF
Usage: $(basename "$0") [options] <command-args>*

Generate meson.build files from a directory tree containing YAML files and
facilitate building the sdbus++ sources.

Options:
    --help              - Display this message
    --command <cmd>     - Command mode to execute (default 'meson').
    --directory <path>  - Root directory of the YAML source (default '.').
    --output <path>     - Root directory of the output (default '.').
    --tool <path>       - Path to the processing tool (default 'sdbus++').
    --version           - Display this tool's version string.

Commands:
    meson               - Generate a tree of meson.build files corresponding
                          to the source YAML files.
    cpp <intf>          - Generate the source files from a YAML interface.
    markdown <intf>     - Generate the markdown files from a YAML interface.
    version             - Display this tool's version string.

EOF
}

## The version is somewhat arbitrary but is used to create a warning message
## if a repository contains old copies of the generated meson.build files and
## needs an update.  We should increment the version number whenever the
## resulting meson.build would change.
tool_version="sdbus++-gen-meson version 3"
function show_version {
    echo "${tool_version}"
}

# Set up defaults.
sdbuspp="sdbus++"
outputdir="."
cmd="meson"
rootdir="."

# Parse options.
options="$(getopt -o hc:d:o:t:v --long help,command:,directory:,output:,tool:,version -- "$@")"
eval set -- "${options}"

while true; do
    case "$1" in
        -h | --help)
            show_usage
            exit
            ;;

        -c | --command)
            shift
            cmd="$1"
            shift
            ;;

        -d | --directory)
            shift
            rootdir="$1"
            shift
            ;;

        -o | --output)
            shift
            outputdir="$1"
            shift
            ;;

        -t | --tool)
            shift
            sdbuspp="$1"
            shift
            ;;

        -v | --version)
            show_version
            exit
            ;;

        --)
            shift
            break
            ;;

        *)
            echo "Invalid argument $1"
            exit 1
            ;;
    esac
done

## Create an initially empty meson.build file.
## $1 - path to create meson.build at.
function meson_empty_file {
    mkdir -p "$1"
    echo "# Generated file; do not modify." > "$1/meson.build"
}

## Create the root-level meson.build
##
## Inserts rules to run the available version of this tool to ensure the
## version has not changed.
function meson_create_root {
    meson_empty_file "${outputdir}"

    cat >> "${outputdir}/meson.build" \
        << EOF
sdbuspp_gen_meson_ver = run_command(
    sdbuspp_gen_meson_prog,
    '--version',
).stdout().strip().split('\n')[0]

if sdbuspp_gen_meson_ver != '${tool_version}'
    warning('Generated meson files from wrong version of sdbus++-gen-meson.')
    warning(
        'Expected "${tool_version}", got:',
        sdbuspp_gen_meson_ver
    )
endif

EOF
}

## hash-tables to store:
##      meson_paths - list of subdirectory paths for which an empty meson.build
##                    has already been created.
##      interfaces - list of interface paths which a YAML has been found and
##                   which YAML types (interface, errors, etc.).
declare -A meson_paths
declare -A interfaces

## Ensure the meson.build files to a path have been created.
## $1 - The path requiring to be created.
function meson_create_path {

    meson_path="${outputdir}"
    prev_meson_path=""

    # Split the path into segments.
    for part in $(echo "$1" | tr '/' '\n'); do
        prev_meson_path="${meson_path}"
        meson_path="${meson_path}/${part}"

        # Create the meson.build for this segment if it doesn't already exist.
        if [[ "" == "${meson_paths[${meson_path}]}" ]]; then
            meson_paths["${meson_path}"]="1"
            meson_empty_file "${meson_path}"

            # Add the 'subdir' link into the parent's meson.build.
            # We need to skip adding the links into the 'root' meson.build
            # because most repositories want to selectively add TLDs based
            # on config flags.  Let them figure out their own logic for that.
            if [[ ${outputdir} != "${prev_meson_path}" ]]; then
                echo "subdir('${part}')" >> "${prev_meson_path}/meson.build"
            fi
        fi
    done
}

## Generate the meson target for the source files (.cpp/.hpp) from a YAML
## interface.
##
## $1 - The interface to generate a target for.
function meson_cpp_target {
    mesondir="${outputdir}/$1"
    yamldir="$(realpath --relative-to="${mesondir}" "${rootdir}")"

    # Determine the source and output files based on the YAMLs present.
    sources=""
    outputs=""
    for s in ${interfaces[$1]}; do
        sources="'${yamldir}/$1.${s}', "

        case "${s}" in
            errors.yaml)
                outputs="${outputs}'error.cpp', 'error.hpp', "
                ;;

            interface.yaml)
                outputs="${outputs}'server.cpp', 'server.hpp', "
                outputs="${outputs}'client.hpp', "
                ;;

            *)
                echo "Unknown interface type: ${s}"
                exit 1
                ;;
        esac
    done

    # Create the target to generate the 'outputs'.
    cat >> "${mesondir}/meson.build" \
        << EOF
generated_sources += custom_target(
    '$1__cpp'.underscorify(),
    input: [ ${sources} ],
    output: [ ${outputs} ],
    command: [
        sdbuspp_gen_meson_prog, '--command', 'cpp',
        '--output', meson.current_build_dir(),
        '--tool', sdbusplusplus_prog,
        '--directory', meson.current_source_dir() / '${yamldir}',
        '$1',
    ],
)

EOF
}

## Generate the meson target for the markdown files from a YAML interface.
## $1 - The interface to generate a target for.
function meson_md_target {
    mesondir="${outputdir}/$(dirname "$1")"
    yamldir="$(realpath --relative-to="${mesondir}" "${rootdir}")"

    # Determine the source files based on the YAMLs present.
    sources=""
    for s in ${interfaces[$1]}; do
        sources="'${yamldir}/$1.${s}', "
    done

    # Create the target to generate the interface.md file.
    cat >> "${mesondir}/meson.build" \
        << EOF
generated_others += custom_target(
    '$1__markdown'.underscorify(),
    input: [ ${sources} ],
    output: [ '$(basename "$1").md' ],
    command: [
        sdbuspp_gen_meson_prog, '--command', 'markdown',
        '--output', meson.current_build_dir(),
        '--tool', sdbusplusplus_prog,
        '--directory', meson.current_source_dir() / '${yamldir}',
        '$1',
    ],
)

EOF
}

## Handle command=meson by generating the tree of meson.build files.
function cmd_meson {
    TLDs="com net org xyz"
    yamls=""

    # Find all the YAML files in the TLD subdirectories.
    for d in ${TLDs}; do
        dir="${rootdir}/${d}"
        if [[ ! -d ${dir} ]]; then
            continue
        fi

        yamls="\
            ${yamls} \
            $(find "${dir}" -name '*.interface.yaml' -o -name '*.errors.yaml') \
            "
    done

    # Sort YAMLs
    # shellcheck disable=SC2312
    yamls="$(echo "${yamls}" | tr " " "\n" | sort)"

    # Assign the YAML files into the hash-table by interface name.
    for y in ${yamls}; do
        rel="$(realpath "--relative-to=${rootdir}" "${y}")"
        dir="$(dirname "${rel}")"
        ext="${rel#*.}"
        base="$(basename "${rel}" ".${ext}")"
        key="${dir}/${base}"

        interfaces["${key}"]="${interfaces[${key}]} ${ext}"
    done

    # Create the meson.build files.
    meson_create_root
    # shellcheck disable=SC2312
    sorted_ifaces="$(echo "${!interfaces[@]}" | tr " " "\n" | sort)"
    for i in ${sorted_ifaces}; do
        meson_create_path "${i}"
        meson_cpp_target "${i}"
        meson_md_target "${i}"
    done
}

## Handle command=cpp by calling sdbus++ as appropriate.
## $1 - interface to generate.
##
## For an interface foo/bar, the outputdir is expected to be foo/bar.
function cmd_cpp {

    if [[ "" == "$1" ]]; then
        show_usage
        exit 1
    fi

    if [[ ! -e "${rootdir}/$1.interface.yaml" ]] &&
        [[ ! -e "${rootdir}/$1.errors.yaml" ]]; then
        echo "Missing YAML for $1."
        exit 1
    fi

    mkdir -p "${outputdir}"

    sdbusppcmd="${sdbuspp} -r ${rootdir}"
    intf="${1//\//.}"

    if [[ -e "${rootdir}/$1.interface.yaml" ]]; then
        ${sdbusppcmd} interface server-header "${intf}" > "${outputdir}/server.hpp"
        ${sdbusppcmd} interface server-cpp "${intf}" > "${outputdir}/server.cpp"
        ${sdbusppcmd} interface client-header "${intf}" > "${outputdir}/client.hpp"
    fi

    if [[ -e "${rootdir}/$1.errors.yaml" ]]; then
        ${sdbusppcmd} error exception-header "${intf}" > "${outputdir}/error.hpp"
        ${sdbusppcmd} error exception-cpp "${intf}" > "${outputdir}/error.cpp"
    fi
}

## Handle command=markdown by calling sdbus++ as appropriate.
## $1 - interface to generate.
##
## For an interface foo/bar, the outputdir is expected to be foo.
function cmd_markdown {

    if [[ "" == "$1" ]]; then
        show_usage
        exit 1
    fi

    if [[ ! -e "${rootdir}/$1.interface.yaml" ]] &&
        [[ ! -e "${rootdir}/$1.errors.yaml" ]]; then
        echo "Missing YAML for $1."
        exit 1
    fi

    mkdir -p "${outputdir}"

    sdbusppcmd="${sdbuspp} -r ${rootdir}"
    intf="${1//\//.}"
    base="$(basename "$1")"

    echo -n > "${outputdir}/${base}.md"
    if [[ -e "${rootdir}/$1.interface.yaml" ]]; then
        ${sdbusppcmd} interface markdown "${intf}" >> "${outputdir}/${base}.md"
    fi

    if [[ -e "${rootdir}/$1.errors.yaml" ]]; then
        ${sdbusppcmd} error markdown "${intf}" >> "${outputdir}/${base}.md"
    fi
}

## Handle command=version.
function cmd_version {
    show_version
}

"cmd_${cmd}" "$*"