#!/usr/bin/bash

DEFAULT_MIRRORLIST="/etc/pacman.d/mirrorlist"
DEFAULT_KERNEL="linux-cachyos"
PROPAGATE_MANJARO="Keep all currently installed Manjaro kernels"

# yes, they're hard-coded. For now at least.
KNOWN_KERNELS=(
    "$PROPAGATE_MANJARO"
    "linux"
    "linux-lts"
    "linux-hardened"
    "linux-rt"
    "linux-cachyos"
    "linux-cachyos-lts"
    "linux-cachyos-hardened"
    "linux-cachyos-bore"
    "linux-cachyos-eevdf"
    "linux-cachyos-bmq"
    "linux-cachyos-deckify"
    "linux-cachyos-rc"
    "linux-cachyos-rt-bore"
    "linux-cachyos-server"
    "linux-zen"
    #"linux-cachyos-cacule"
    #"linux-cachyos-debug"
    #"linux-cachyos-gcc"
)

RED="\e[31m"
GREEN="\e[32m"
ERASE='\033[0m'

USERNAME=$(logname)

run_unprivileged() {
    sudo -u "$USERNAME" "$@"
}

is_installed() {
    which "$1" > /dev/null
    [ $? -eq 0 ]
    return $?
}

assert() {
    if ! $1; then
        echo "Script depends on $2 to function, please resolve manually."
        exit 1
    fi

    # Yes, this is always true, but anyway.
    return 0
}

# Credit to NaN on StackOverflow for this solution.
# https://stackoverflow.com/questions/29436275/how-to-prompt-for-yes-or-no-in-bash
prompt_bool() {
    if $2; then
        options="[Y/n]"
        default="y"
    else
        options="[y/N]"
        default="n"
    fi

    echo -ne "$1 $options: "
    read -r tmp
    tmp=${tmp:-${default}}

    [[ "$tmp" =~ ^[yY]$ ]]
    return $?
}

log() {
    echo -e "${GREEN}[INFO] $1$ERASE"
}

if [[ $(id -u) > 0 ]]; then
    echo -e "${RED}[ERROR] Script requires elevated permissions.${ERASE}"
    exit 1
fi

# Needs to be this funky to avoid fetching ase, base-devel, and filesystem.
# For some reason, pacman -Qqs "manjaro" will do that.
log "Checking for soon-to-be Manjaro orphans..."
deps_remove=(
    $(pacman -Qqs "manjaro-")
    $(pacman -Qqs "\-manjaro")
    $(pacman -Qqs "\-breath")
    pacman-mirrors
)
printf "Found:\n${deps_remove[@]}\n"

log "Checking for Pamac..."
deps_pamac=$(pacman -Qqs pamac)
deps_remove+=($deps_pamac)
printf "Found:\n${deps_pamac[@]}\n"

log "Checking for mhwd..."
deps_mhwd=$(pacman -Qqs mhwd)
deps_remove+=($deps_mhwd)
printf "Found:\n${deps_mhwd[@]}\n"

log "Checking additional installs and package migrations..."
deps_install=()

prompt_bool "Install proton-cachyos-slr?" true
if [[ $? ]]; then
    deps_install+=("proton-cachyos-slr")
fi

prompt_bool "Install protonup-qt?" true
if [[ $? ]]; then
    deps_install+=("protonup-qt")
fi

log "Checking for KDE..."
if [[ $(echo $XDG_CURRENT_DESKTOP | grep -i "kde") ]]; then
    # Default to not changing because it doesn't work for shit on
    # either of the systems I've tried it on.
    prompt_bool "Replace sddm with plasma-login-manager?" false
    if [[ $? ]]; then
        deps_install+=("plasma-login-manager")
        deps_remove+=("sddm")
        deps_remove+=("sddm-kcm")
    fi
fi

log "Checking for Octopi..."
if ! is_installed octopi; then
    prompt_bool "Install Octopi (to replace Pamac)?" true
    if [[ $? ]]; then
        deps_install+=("octopi")
    fi
fi

log "Removing old packages and Manjaro orphans..."
pacman -Rdd "${deps_remove[@]}"

log "Checking for reflector..."
if ! is_installed reflector; then
    pacman -S yay
    assert $(is_installed yay) "yay"

    run_unprivileged yay -S reflector
    assert $(is_installed reflector) "reflector"
fi

# REPOS
# Install CachyOS Repos
# See: https://wiki.cachyos.org/features/optimized_repos/#adding-our-repositories-to-an-existing-arch-linux-install
log "Installing CachyOS repos..."
cd $(mktemp -d)
curl https://mirror.cachyos.org/cachyos-repo.tar.xz -o cachyos-repo.tar.xz
tar xvf cachyos-repo.tar.xz
cd cachyos-repo

# Just in case, ensure the script can be executed.
if [[ ! -x "cachyos-repo.sh" ]]; then
    chmod +x cachyos-repo.sh
fi

./cachyos-repo.sh

# Backup Manjaro Repos
log "Backing up Manjaro mirrorlist..."
mv "$DEFAULT_MIRRORLIST" "$DEFAULT_MIRRORLIST.bak"

# Install Arch Repos
log "Installing Arch Linux repos..."
curl -o "$DEFAULT_MIRRORLIST" "https://archlinux.org/mirrorlist/all/"

log "Refreshing Arch mirrors..."
reflector\
    --fastest "32"\
    --protocol "https"\
    --sort "rate"\
    --save "$DEFAULT_MIRRORLIST"
pacman -Syy

log "Checking for chwd..."
if ! is_installed chwd; then
    pacman -Sdd chwd
    assert $(is_installed chwd) "chwd"
fi

# INSTALL NEW KERNEL(S)
log "Installing new kernel(s)..."
# List available kernels
for idx in "${!KNOWN_KERNELS[@]}"; do
    printf "%s\t%s\n" "$idx" "${KNOWN_KERNELS[$idx]}"
done

echo
echo -n "Kernel(s): "
read -r tmp

if [[ ${#tmp} > 0 ]]; then
    # Credit to bgoldst on StackOverflow for this solution.
    # https://stackoverflow.com/questions/10586153/how-to-split-a-string-into-an-array-in-bash
    readarray -td, kernels <<< "$tmp,"
    unset 'kernels[-1]'
    declare -p kernels

    tmp=()
    for idx in "${kernels[@]}"; do
        if [[ $idx != 0 ]]; then
            tmp+=("${KNOWN_KERNELS[$idx]}")
        fi
    done
    kernels=(${tmp[@]})
else
    kernels="$DEFAULT_KERNEL"
fi

# TODO: Install kernels
log "Installing desired kernels..."
if [[ ${#kernels} != 0 ]]; then
    pacman -S --noconfirm ${kernels[@]}
else
    echo "No new kernels, skipping."
fi

log "Fetching all system packages to replace with CachyOS+Arch packages..."
# Credit to https://insrt.uk/post/pacman-reinstall for this solution.
deps_install+=($(comm -12 <(pacman -Slq | sort -u) <(pacman -Qq | sort -u)))

log "Installing new packages..."
pacman -Sdd ${deps_install[@]}

chwd --autoconfigure

if [[ $(is_installed plasmalogin) && $(systemctl is-enabled sddm) ]]; then
    systemctl disable sddm
    systemctl enable plasmalogin
fi

log "Done."
echo "Quick reminder: Be prepared to fix things!"
echo "Many orphaned packages will still exist on the system, and should be"
echo "removed to reduce the system's attack surface. This may also prevent"
echo "issues down the line due to incompatibilities between CachyOS+Arch and"
echo "various Manjaro hacks."
echo
echo "It is recommended to install Octopi and look for packages prefixed with"
echo "'manjaro-' and remove them. Also check packages which have fallen back"
echo "to being sourced from the AUR."