#!/bin/bash

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(dirname "$SCRIPT_DIR")"
REBOOT_MARKER="$REPO_ROOT/.setup-reboot-required"
REPO_SECRET_FILE="$REPO_ROOT/Zsh/.zsh_secrets"
HOME_SECRET_FILE="$HOME/.zsh_secrets"
BACKUP_ROOT="$HOME/.dotzsh-pre-stow-backup"

handle_reboot_marker() {
    if [ -f "$REBOOT_MARKER" ]; then
        rm -f "$REBOOT_MARKER"
        echo "Package layering finished. Reboot, then rerun the same command."
        exit 0
    fi
}

sync_repo_managed_secret_file() {
    local home_secret_resolved repo_secret_resolved

    mkdir -p "$(dirname "$REPO_SECRET_FILE")"

    if [ -L "$HOME_SECRET_FILE" ]; then
        home_secret_resolved="$(python3 -c 'import os,sys; print(os.path.realpath(sys.argv[1]))' "$HOME_SECRET_FILE")"
        repo_secret_resolved="$(python3 -c 'import os,sys; print(os.path.realpath(sys.argv[1]))' "$REPO_SECRET_FILE")"

        if [ "$home_secret_resolved" = "$repo_secret_resolved" ]; then
            return 0
        fi

        if [ -f "$home_secret_resolved" ]; then
            if [ ! -f "$REPO_SECRET_FILE" ] || [ ! -s "$REPO_SECRET_FILE" ]; then
                cp "$home_secret_resolved" "$REPO_SECRET_FILE"
                rm -f "$HOME_SECRET_FILE"
                return 0
            fi

            if cmp -s "$home_secret_resolved" "$REPO_SECRET_FILE"; then
                rm -f "$HOME_SECRET_FILE"
                return 0
            fi
        fi

        echo "Conflict: $HOME_SECRET_FILE points to a different secret file than $REPO_SECRET_FILE."
        echo "Please merge them manually, then rerun the command."
        exit 1
    fi

    if [ -f "$HOME_SECRET_FILE" ]; then
        if [ ! -f "$REPO_SECRET_FILE" ] || [ ! -s "$REPO_SECRET_FILE" ]; then
            mv "$HOME_SECRET_FILE" "$REPO_SECRET_FILE"
            return 0
        fi

        if cmp -s "$HOME_SECRET_FILE" "$REPO_SECRET_FILE"; then
            rm -f "$HOME_SECRET_FILE"
            return 0
        fi

        echo "Conflict: both $HOME_SECRET_FILE and $REPO_SECRET_FILE exist with different contents."
        echo "Please merge them manually, then rerun the command."
        exit 1
    fi

    touch "$REPO_SECRET_FILE"
}

backup_conflicting_home_files() {
    local backup_dir backed_up_any=0 source_file filename target_file target_resolved source_resolved

    backup_dir="$BACKUP_ROOT/$(date +%Y%m%d-%H%M%S)"

    while IFS= read -r source_file; do
        filename="$(basename "$source_file")"
        target_file="$HOME/$filename"

        if [ -L "$target_file" ]; then
            target_resolved="$(python3 -c 'import os,sys; print(os.path.realpath(sys.argv[1]))' "$target_file")"
            source_resolved="$(python3 -c 'import os,sys; print(os.path.realpath(sys.argv[1]))' "$source_file")"

            if [ "$target_resolved" = "$source_resolved" ]; then
                continue
            fi

            mkdir -p "$backup_dir"
            mv "$target_file" "$backup_dir/$filename"
            echo "Backed up existing linked $target_file -> $backup_dir/$filename"
            backed_up_any=1
        elif [ -e "$target_file" ]; then
            mkdir -p "$backup_dir"
            mv "$target_file" "$backup_dir/$filename"
            echo "Backed up existing $target_file -> $backup_dir/$filename"
            backed_up_any=1
        fi
    done < <(find "$REPO_ROOT/Zsh" -mindepth 1 -maxdepth 1 -type f -name '.*' ! -name '.zsh_secrets')

    if [ "$backed_up_any" -eq 1 ]; then
        echo "Existing unmanaged dotfiles were backed up before stowing."
    fi
}

stow_dotfiles() {
    echo "Preparing repo-managed secrets for stow..."
    sync_repo_managed_secret_file

    echo "Checking for conflicting home dotfiles before stow..."
    backup_conflicting_home_files

    echo "Cleaning existing Zsh stow links..."
    stow --dir="$REPO_ROOT" -D Zsh --target="$HOME" 2>/dev/null || true

    echo "Stowing Zsh dotfiles..."
    stow --dir="$REPO_ROOT" Zsh --target="$HOME"

    echo "Zsh dotfiles stowed."
}

bootstrap_only() {
    rm -f "$REBOOT_MARKER"

    bash "$SCRIPT_DIR/base.sh"
    handle_reboot_marker

    stow_dotfiles

    echo "Bootstrap setup completed."
}

full_setup() {
    rm -f "$REBOOT_MARKER"

    bash "$SCRIPT_DIR/base.sh"
    handle_reboot_marker

    bash "$SCRIPT_DIR/node.sh"
    bash "$SCRIPT_DIR/go.sh"
    bash "$SCRIPT_DIR/rust.sh"
    bash "$SCRIPT_DIR/python.sh"
    handle_reboot_marker

    bash "$SCRIPT_DIR/r.sh"
    handle_reboot_marker

    stow_dotfiles

    echo "Full setup completed."
}

case "${1:-}" in
    --bootstrap-only)
        bootstrap_only
        ;;
    --stow-only)
        stow_dotfiles
        ;;
    "")
        full_setup
        ;;
    *)
        echo "Usage: $0 [--bootstrap-only|--stow-only]"
        exit 1
        ;;
esac