#!/bin/bash
# pr-diff.sh - Get the diff for a pull request on GitHub or Gitea
# Usage: pr-diff.sh -n <pr_number> [-o <output_file>]

set -e

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/detect-platform.sh"

# Parse arguments
PR_NUMBER=""
OUTPUT_FILE=""

while [[ $# -gt 0 ]]; do
    case $1 in
        -n|--number)
            PR_NUMBER="$2"
            shift 2
            ;;
        -o|--output)
            OUTPUT_FILE="$2"
            shift 2
            ;;
        -h|--help)
            echo "Usage: pr-diff.sh -n <pr_number> [-o <output_file>]"
            echo ""
            echo "Options:"
            echo "  -n, --number   PR number (required)"
            echo "  -o, --output   Output file (optional, prints to stdout if omitted)"
            echo "  -h, --help     Show this help"
            exit 0
            ;;
        *)
            echo "Unknown option: $1"
            exit 1
            ;;
    esac
done

if [[ -z "$PR_NUMBER" ]]; then
    echo "Error: PR number is required (-n)" >&2
    exit 1
fi

detect_platform > /dev/null

if [[ "$PLATFORM" == "github" ]]; then
    if [[ -n "$OUTPUT_FILE" ]]; then
        gh pr diff "$PR_NUMBER" > "$OUTPUT_FILE"
    else
        gh pr diff "$PR_NUMBER"
    fi
elif [[ "$PLATFORM" == "gitea" ]]; then
    # tea doesn't have a direct diff command — use the API
    OWNER=$(get_repo_owner)
    REPO=$(get_repo_name)
    REMOTE_URL=$(git remote get-url origin 2>/dev/null)

    # Extract host from remote URL
    if [[ "$REMOTE_URL" == https://* ]]; then
        HOST=$(echo "$REMOTE_URL" | sed -E 's|https://([^/]+)/.*|\1|')
    elif [[ "$REMOTE_URL" == git@* ]]; then
        HOST=$(echo "$REMOTE_URL" | sed -E 's|git@([^:]+):.*|\1|')
    else
        echo "Error: Cannot determine host from remote URL" >&2
        exit 1
    fi

    DIFF_URL="https://${HOST}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}.diff"

    GITEA_API_TOKEN=$(get_gitea_token "$HOST" || true)

    if [[ -n "$GITEA_API_TOKEN" ]]; then
        DIFF_CONTENT=$(curl -sS -H "Authorization: token $GITEA_API_TOKEN" "$DIFF_URL")
    else
        DIFF_CONTENT=$(curl -sS "$DIFF_URL")
    fi

    if [[ -n "$OUTPUT_FILE" ]]; then
        echo "$DIFF_CONTENT" > "$OUTPUT_FILE"
    else
        echo "$DIFF_CONTENT"
    fi
else
    echo "Error: Unknown platform" >&2
    exit 1
fi