#!/usr/bin/env bash
# 下載 JPL 星曆表檔案用於陰曆計算
# 使用方式: ./download_ephemeris.sh [de421|de422|de440s|all]
# 預設: de421

set -e

# 輸出顏色
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # 無顏色

# JPL 星曆表檔案下載網址
BASE_URL="https://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/planets"

# 檔案資訊: 名稱 大小mb 說明
declare -A FILES=(
    ["de421"]="de421.bsp 15 JPL DE421 (1900-2050, ~15MB)"
    ["de422"]="de422.bsp 500 JPL DE422 (較長時期範圍, ~500MB)"
    ["de440s"]="de440s.bsp 30 JPL DE440s (1900-2150, ~30MB)"
)

# 輸出資訊
print_info() {
    echo -e "${GREEN}[資訊]${NC} $1"
}

# 輸出警告
print_warn() {
    echo -e "${YELLOW}[警告]${NC} $1"
}

# 輸出錯誤
print_error() {
    echo -e "${RED}[錯誤]${NC} $1"
}

# 下載檔案
download_file() {
    local name=$1
    local url=$2
    local filename=$(basename "$url")

    print_info "正在下載 $filename..."

    if [ -f "$filename" ]; then
        print_warn "$filename 已存在，跳過下載"
        return 0
    fi

    if curl -L -o "$filename" "$url"; then
        print_info "$filename 下載完成"
        return 0
    else
        print_error "$filename 下載失敗"
        return 1
    fi
}

# 驗證檔案大小
verify_file() {
    local filename=$1
    local expected_size_mb=$2

    if [ ! -f "$filename" ]; then
        print_error "檔案 $filename 不存在"
        return 1
    fi

    local actual_size=$(du -m "$filename" | cut -f1)

    if [ "$actual_size" -lt 1 ]; then
        print_error "$filename 檔案大小異常"
        rm -f "$filename"
        return 1
    fi

    print_info "$filename 檔案大小: ${actual_size}MB"
    return 0
}

# 主下載函式
download_ephemeris() {
    local target=${1:-de421}

    case "$target" in
        de421)
            print_info "下載 DE421 (推薦，涵蓋 1900-2050)"
            download_file "de421" "$BASE_URL/a_old_versions/de421.bsp"
            verify_file "de421.bsp" 15
            ;;
        de422)
            print_info "下載 DE422 (大檔案，涵蓋更長時間)"
            print_warn "DE422 約 500MB，下載可能需要較長時間..."
            download_file "de422" "$BASE_URL/a_old_versions/de422.bsp"
            verify_file "de422.bsp" 500
            ;;
        de440s)
            print_info "下載 DE440s (精簡版，涵蓋 1900-2150)"
            download_file "de440s" "$BASE_URL/de440s.bsp"
            verify_file "de440s.bsp" 30
            ;;
        all)
            print_info "下載所有星曆表檔案"
            for key in "${!FILES[@]}"; do
                download_ephemeris "$key"
                echo
            done
            ;;
        list)
            echo "可用的星曆表檔案:"
            for key in "${!FILES[@]}"; do
                echo "  - $key: ${FILES[$key]}"
            done
            ;;
        *)
            print_error "未知的選項: $target"
            echo
            echo "用法: $0 [de421|de422|de440s|all|list]"
            echo
            echo "說明:"
            for key in "${!FILES[@]}"; do
                echo "  $key - ${FILES[$key]}"
            done
            exit 1
            ;;
    esac
}

# 無參數時顯示說明
if [ $# -eq 0 ]; then
    echo "下載 JPL 星曆表檔案"
    echo
    echo "用法: $0 [de421|de422|de440s|all|list]"
    echo
    echo "預設下載: de421"
    echo
    download_ephemeris "list"
    echo
    read -p "按 Enter 下載 de421，或按 Ctrl+C 取消..."
    download_ephemeris "de421"
else
    download_ephemeris "$1"
fi

print_info "完成！"