#!/usr/bin/env bash
#
# download-prefill.sh
#
# Downloads the latest (or specific) release of SteamPrefill
# (https://github.com/tpill90/steam-lancache-prefill) into
# bin/steam-prefill/SteamPrefill
#
# Usage:
#   ./scripts/download-prefill.sh
#
# Environment:
#   PREFILL_VERSION   - Pin a specific version tag (e.g. v3.4.2)
#   PREFILL_FORCE     - Set to any non-empty value to re-download even if present
#
set -euo pipefail

DEST_DIR="bin/steam-prefill"
TARGET="$DEST_DIR/SteamPrefill"

mkdir -p "$DEST_DIR"

if [[ -x "$TARGET" && -z "${PREFILL_FORCE:-}" ]]; then
    echo "SteamPrefill already present at $TARGET"
    echo "Run with PREFILL_FORCE=1 to re-download."
    exit 0
fi

VERSION="${PREFILL_VERSION:-}"

OS=$(uname -s | tr '[:upper:]' '[:lower:]')
ARCH=$(uname -m)

case "$ARCH" in
    x86_64|amd64)  ARCH_NAME="x64" ;;
    aarch64|arm64) ARCH_NAME="arm64" ;;
    *) echo "Unsupported architecture: $ARCH"; exit 1 ;;
esac

case "$OS" in
    linux)  OS_NAME="linux" ;;
    darwin) OS_NAME="osx" ;;
    *) echo "Unsupported OS: $OS"; exit 1 ;;
esac

echo "Resolving SteamPrefill version..."

if [[ -z "$VERSION" ]]; then
    # Follow the /latest redirect to discover the current tag
    LATEST_URL=$(curl -sIL -o /dev/null -w '%{url_effective}' \
        "https://github.com/tpill90/steam-lancache-prefill/releases/latest" 2>/dev/null || true)

    if [[ "$LATEST_URL" =~ /tag/([^/?#]+) ]]; then
        VERSION="${BASH_REMATCH[1]}"
    else
        echo "Failed to resolve latest version from GitHub redirect."
        exit 1
    fi
fi

echo "Downloading SteamPrefill $VERSION for ${OS_NAME}-${ARCH_NAME}..."

rm -f "$TARGET" "$TARGET.tmp" 2>/dev/null || true

DOWNLOADED=0

# Preferred: query the GitHub API for the exact asset list (most reliable)
API_URL="https://api.github.com/repos/tpill90/steam-lancache-prefill/releases/tags/${VERSION}"
ASSET_URL=""

if command -v jq >/dev/null 2>&1; then
    echo "  Querying GitHub API for assets..."
    ASSET_NAME=$(curl -fsSL "$API_URL" 2>/dev/null | jq -r --arg os "$OS_NAME" --arg arch "$ARCH_NAME" '
        .assets[]
        | select(.name | ascii_downcase | contains($os))
        | select(.name | ascii_downcase | contains($arch))
        | .name
    ' | head -1)

    if [[ -n "$ASSET_NAME" ]]; then
        ASSET_URL="https://github.com/tpill90/steam-lancache-prefill/releases/download/${VERSION}/${ASSET_NAME}"
        echo "  Found asset via API: $ASSET_NAME"
    fi
fi

# Fallback: try common name patterns if API or jq not available
if [[ -z "$ASSET_URL" ]]; then
    echo "  Trying common asset name patterns..."
    CANDIDATES=(
        "SteamPrefill-${VERSION}-${OS_NAME}-${ARCH_NAME}.zip"
        "SteamPrefill-${VERSION}-${OS_NAME}-${ARCH_NAME}"
        "SteamPrefill-${OS_NAME}-${ARCH_NAME}.zip"
        "SteamPrefill-${OS_NAME}-${ARCH_NAME}"
        "SteamPrefill-linux-${ARCH_NAME}.zip"
        "SteamPrefill-linux-${ARCH_NAME}"
    )

    for name in "${CANDIDATES[@]}"; do
        URL="https://github.com/tpill90/steam-lancache-prefill/releases/download/${VERSION}/${name}"
        echo "    Trying $name ..."
        if curl -fI -s --retry 2 "$URL" >/dev/null 2>&1; then
            ASSET_URL="$URL"
            ASSET_NAME="$name"
            break
        fi
    done
fi

if [[ -n "$ASSET_URL" ]]; then
    echo "Downloading $ASSET_NAME ..."
    if curl -fL --retry 3 --retry-delay 2 -A "Mozilla/5.0 (compatible; SteamPrefill-Downloader)" \
            --progress-bar -o "$TARGET.tmp" "$ASSET_URL"; then

        echo "Download complete."

        if [[ "$ASSET_NAME" == *.zip ]]; then
            echo "Extracting..."
            if ! command -v unzip >/dev/null 2>&1; then
                echo "Error: unzip is required for this release."
                rm -f "$TARGET.tmp"
                exit 1
            fi
            unzip -o -q "$TARGET.tmp" -d "$DEST_DIR"
            FOUND=$(find "$DEST_DIR" -type f -name "SteamPrefill" | head -1)
            if [[ -n "$FOUND" ]]; then
                mv "$FOUND" "$TARGET"
            fi
            rm -f "$TARGET.tmp"
            find "$DEST_DIR" -mindepth 1 -maxdepth 1 -type d -name "SteamPrefill*" -exec rm -rf {} + 2>/dev/null || true
        else
            mv "$TARGET.tmp" "$TARGET"
        fi

        chmod +x "$TARGET"
        DOWNLOADED=1
    fi
fi

if [[ $DOWNLOADED -eq 0 ]]; then
    echo ""
    echo "Failed to download a matching asset for $VERSION."
    echo "You can try pinning a different version:"
    echo "  PREFILL_VERSION=vX.Y.Z ./scripts/download-prefill.sh"
    echo ""
    echo "Or download manually from:"
    echo "  https://github.com/tpill90/steam-lancache-prefill/releases/tag/${VERSION}"
    exit 1
fi

echo ""
echo "Installed SteamPrefill $VERSION → $TARGET"
echo ""
echo "You can now run it directly, for example:"
echo "  ./bin/steam-prefill/SteamPrefill --help"
echo "  ./bin/steam-prefill/SteamPrefill benchmark run ..."