#!/bin/bash
set -e

PACKAGE_NAME="$1"
LHS_VERSION="$2"
RHS_VERSION="$3"
WORKING_DIR="$4"
REGISTRY="$5"
DIFF_OPTIONS="$6"
OUTPUT_FILE="$7"
FAIL_ON_DIFF="$8"

if [[ ! -f "$GITHUB_OUTPUT" ]]; then
    GITHUB_OUTPUT="/dev/fd/1"
fi

# Change to working directory if specified
if [[ -n "$WORKING_DIR" && "$WORKING_DIR" != "." ]]; then
    cd "$WORKING_DIR"
fi

# Configure npm registry
if [[ -n "$REGISTRY" && "$REGISTRY" != "https://registry.npmjs.org" ]]; then
    npm config set registry "$REGISTRY"
fi

# Build the npm diff command
DIFF_CMD="npm diff"

# Add package specs using correct --diff syntax
if [[ -n "$PACKAGE_NAME" ]]; then
    if [[ -n "$LHS_VERSION" && -n "$RHS_VERSION" ]]; then
        # Compare two specific published versions (LHS as "from", RHS as "to")
        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME@$LHS_VERSION --diff=$PACKAGE_NAME@$RHS_VERSION"
    elif [[ -n "$LHS_VERSION" ]]; then
        # Compare local/installed to the specified LHS version
        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME@$LHS_VERSION"
    elif [[ -n "$RHS_VERSION" ]]; then
        # Compare local/installed to the specified RHS version
        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME@$RHS_VERSION"
    else
        # Compare local/installed to the latest published version
        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME"
    fi
else
    # No package name provided: compare current workspace to its latest published version
    # (standard behavior of plain `npm diff` in a package directory)
    :
fi

# Add any additional diff options (e.g., --diff-name-only, file paths for filtering, etc.)
if [[ -n "$DIFF_OPTIONS" ]]; then
    DIFF_CMD="$DIFF_CMD $DIFF_OPTIONS"
fi

echo "Running: $DIFF_CMD"

# Run npm diff and capture output
DIFF_OUTPUT=$(eval "$DIFF_CMD" 2>&1) || DIFF_EXIT_CODE=$?

# npm diff returns exit code 0 if no differences, 1 if differences found
if [[ -z "$DIFF_EXIT_CODE" ]]; then
    DIFF_EXIT_CODE=0
fi

# Determine if differences were found
if [[ $DIFF_EXIT_CODE -eq 0 ]]; then
    HAS_DIFFERENCES="false"
    echo "No differences found"
else
    HAS_DIFFERENCES="true"
    echo "Differences found"
fi

# Save diff output to file if specified
if [[ -n "$OUTPUT_FILE" ]]; then
    echo "$DIFF_OUTPUT" > "$OUTPUT_FILE"
    echo "Diff output saved to $OUTPUT_FILE"
fi

# Output the diff to console
if [[ -n "$DIFF_OUTPUT" ]]; then
    echo "========== DIFF OUTPUT =========="
    echo "$DIFF_OUTPUT"
    echo "================================="
fi

# Set output variables (truncate diffOutput if too large)
echo "hasDifferences=$HAS_DIFFERENCES" >> "$GITHUB_OUTPUT"

# Truncate diff output for GitHub Actions output (max ~1MB)
TRUNCATED_OUTPUT=$(echo "$DIFF_OUTPUT" | head -c 100000)
if [[ ${#DIFF_OUTPUT} -gt 100000 ]]; then
    TRUNCATED_OUTPUT="$TRUNCATED_OUTPUT... (output truncated)"
fi

# Use multiline output format for GitHub Actions
{
    echo "diffOutput<<EOF"
    echo "$TRUNCATED_OUTPUT"
    echo "EOF"
} >> "$GITHUB_OUTPUT"

# Fail if differences found and failOnDifferences is true
if [[ "$HAS_DIFFERENCES" == "true" && "$FAIL_ON_DIFF" == "true" ]]; then
    echo "Error: Differences found and failOnDifferences is set to true"
    exit 1
fi

exit 0