#!/usr/bin/env bash
set -o pipefail

# Stores release URLs globally to avoid constantly hitting the API server
STENV_RELEASES=()

# Default conda program is "conda"
conda=conda

# Return a list of conda environments matching $1
have_conda_env() {
    if ! have_conda; then
        return 1
    fi
    $conda env list | sed '/^#.*/d' | cut -d ' ' -f 1 \
        | grep "^${1}$" &>/dev/null
}

# Return a comma delimited list of environments matching "stenv"
get_stenv() {
    if ! have_conda; then
        return 1
    fi

    local envs=($($conda env list | sed '/^#.*/d' | cut -d ' ' -f 1 \
        | grep "stenv" | sort -V))

    if (( ${#envs[@]} == 0)); then
        return 1
    fi

    for (( i = 0; i < ${#envs[@]}; i++ )); do
        echo -n "${envs[i]}"
        if (( i < ${#envs[@]} - 1 )); then
            echo -n ", "
        fi
    done
}

# Is conda available?
# return 1 on failure
# return 0 on success
have_conda() {
    type -P $conda &>/dev/null
}

# Get path to conda executable
# return 1 and empty string if conda is not available
# return 0 and path on success
get_conda() {
    if ! have_conda; then
        return 1
    fi
    echo $(type -P $conda)
    return 0
}

# Get CPU architecture
get_arch() {
    uname -m
}

# Convert host platform identifier to a conda-specific string
get_conda_platform() {
    local name=$(uname -s)
    case "$name" in
        Darwin)
            echo "macOSX"
            ;;
        *)
            echo "$name"
            ;;
    esac
}

# Convert host platform identifier to a stenv-specific string
get_stenv_platform() {
    local name=$(uname -s)
    case "$name" in
        Darwin)
            echo "macOS"
            ;;
        *)
            echo "$name"
            ;;
    esac
}

# Return stenv repository data (JSON)
stenv_api() {
    curl -s -X GET "https://api.github.com/repos/spacetelescope/stenv/$1"
}

# Extract release URLs from */stenv/releases
get_stenv_releases() {
    stenv_api releases \
        | grep -Eo '"browser_download_url": "(.*)"' \
        | while read line; do
        sed -e 's/.*: "\(.*\)"/\1/' <<< $line
    done
}

# Extract information from a stenv configuration file name
# returns string:
# name platform python_version stenv_version type
get_stenv_components() {
    local filename=$(basename $1)

    # Handle deprecated config naming convention
    if [[ $filename == "spacetelescope-env"* ]]; then
        filename=${filename/spacetelescope-env/stenv}
    fi
    read st_name st_platform st_python_version st_version st_type \
        <<< $(tr '-' ' ' <<< $filename | sed 's/\.yml//')

    # Immortalize deprecated latest/stable/dev naming convention
    if [[ -z "$st_type" ]]; then
        st_type="latest"
    fi

    echo "$st_name $st_platform ${st_python_version#py} $st_version $st_type"
}

# Main entry point
menu_main() {
    while true; do
        local envs

        echo "STENV Assist"
        echo "============"
        echo

        # Use mamba if its available
        if type -P mamba &>/dev/null; then
            conda=mamba
        fi

        /bin/echo -n "1) Install Conda  " 
        if have_conda; then
            echo -e "\t\t[found: $(get_conda)]"
        else
            echo -e "\t\t[not installed]"
        fi

        /bin/echo -n "2) Install release"
        envs=$(get_stenv)
        if [[ -n "$envs" ]]; then
            echo -e "\t\t[found: $(get_stenv)]"
        else
            echo -e "\t\t[not installed]"
        fi

        echo "q) quit"
        read -p "=> " choice
        case "$choice" in
            1)
                if have_conda; then
                    echo >&2
                    echo "Conda is already installed..." >&2
                    echo >&2
                    continue
                fi
                menu_conda_install
                ;;
            2)
                if ! have_conda; then
                    echo >&2
                    echo "Conda must be:" >&2
                    echo "  - Available on your PATH prior to running stenv_assit" >&2
                    echo "  - [or] Installed using option 1, 'Install Conda'" >&2
                    echo >&2
                    echo "To use an existing Conda installation:" >&2
                    echo "  1. Quit stenv_assit (option: q)" >&2
                    echo "  2. Activate your Conda base environment" >&2
                    echo "  3. Run stenv_assit again" >&2
                    echo >&2
                    continue
                fi
                menu_create_stenv
                ;;
            [Qq])
                exit 0
                ;;
            *)
                echo >&2
                echo "Invalid selection" >&2
                echo >&2
                ;;
        esac
    done
}

# Perform base conda installation
# arguments:
#   url: URL to remote conda installation script
# returns status of "$conda init"
task_conda_install() {
    local url=$1
    local filename=$(basename $1)
    local root

    if [[ "$filename" == "Mini"* ]]; then
        root=$HOME/miniconda3
    elif [[ "$filename" == "Mamba"* ]]; then
        root=$HOME/mambaforge
    else
        echo "Unsupported installer: $url" >&2
        return
    fi

    if [[ -d "$root" ]]; then
        echo
        echo "An existing installation was found:"
        echo "  $root"
        echo
        echo "Do the following:"
        echo "  1. Quit stenv_assist (option: q)"
        echo "  2. Activate $root"
        echo "     Run:"
        echo "       source $root/etc/profile.d/conda.sh"
        if [[ -f "$root"/etc/profile.d/mamba.sh ]]; then
            echo "       source $root/etc/profile.d/mamba.sh"
        fi
        echo "       conda activate base"
        echo "  3. Run stenv_assist again"
        echo
        return 0
    fi

    echo "Downloading... $url"
    curl -L -O "$url"

    echo "Installing... $filename"
    bash "$filename" -p "$root" -b
    rm -f "$filename"

    echo "Configuring shell environment..."
    source "$root"/etc/profile.d/conda.sh
    if [[ -f "$root"/etc/profile.d/mamba.sh ]]; then
        source "$root"/etc/profile.d/mamba.sh
    fi
    $conda init $(basename $SHELL)
}

menu_conda_install() {
    local arch=$(get_arch)
    local platform=$(get_conda_platform)
    local mambaforge=https://github.com/conda-forge/miniforge/releases/latest/download/Mambaforge-${platform}-${arch}.sh
    local miniconda=https://repo.anaconda.com/miniconda/Miniconda3-latest-${platform}-${arch}.sh

    echo
    echo "Choose an installer..."
    echo
    echo "1) mambaforge"
    echo "2) miniconda3"
    echo "b) go back"
    echo "q) quit"

    while true; do
        read -p "=> " choice
        case "$choice" in
            1)
                task_conda_install $mambaforge
                break
                ;;
            2)
                task_conda_install $miniconda
                break
                ;;
            b)
                break
                ;;
            [qQ])
                exit 0
                ;;
            *)
                echo >&2
                echo "Invalid selection" >&2
                echo >&2
                ;;
        esac
    done

}

menu_create_stenv() {
    echo
    echo "Choose a stenv release..."
    echo
    for (( i = 0; i < "${#STENV_RELEASES[@]}"; i++ )); do
        local name="${STENV_RELEASES[i]}"
        read st_name st_platform st_python_version st_version st_type \
            <<< $(get_stenv_components $name)

        printf "%4d) %-20s Python %-10s %-5s[%s]\n" \
            "$i" "$st_version" "$st_python_version" " " "$st_type"
    done
    echo "  b) go back"
    echo "  q) quit"

    while true; do
        local default=$(( ${#STENV_RELEASES[@]} - 1 ))
        read -p "(default: $default) => " choice
        if [[ -z "$choice" ]]; then
            choice=$default
        fi
        case "$choice" in
            [0-9]*)
                if [[ "$choice" =~ [a-Z]+ ]] || (( choice < 0 )) \
                    || (( choice > "${#STENV_RELEASES[@]}" - 1 )); then
                    echo "Index out of range" >&2
                    continue
                fi
                task_create_stenv ${STENV_RELEASES[choice]}
                break
                ;;
            [bB])
                break
                ;;
            [qQ])
                exit 0
                ;;
            *)
                echo >&2
                echo "Invalid selection" >&2
                echo >&2
                ;;
        esac
    done
}

# Perform stenv conda environment creation
# arguments:
#  url: URL of remote stenv YAML configuration
# returns status of "$conda env create"
task_create_stenv() {
    local choice
    local name
    local url="$1"
    read st_name st_platform st_python_version st_version st_type \
        <<< $(get_stenv_components $url)

    name="stenv_py${st_python_version/./}"

    if have_conda_env $name; then
        echo
        read -p "$name environment exists, do you wish to replace it ([y/N])? " choice
        case "$choice" in
            [yY])
                $conda env remove --yes --name "$name"
                # fall through to environment creation
                ;;
            *)
                echo
                return 1
                ;;
        esac
    fi

    echo "Using $url"
    $conda env create --name "$name" --file "$url"
}

# main()

# Populate release array for host system
for x in $(get_stenv_releases | sort -V); do
    if [[ "$x" =~ .*-"$(get_stenv_platform)-".* ]]; then
        STENV_RELEASES+=($x)
    fi
done

# Load the interactive menu system
menu_main