#!/usr/bin/env bash
# check-fork-drift.sh — Detect upstream drift in Red Bear OS local forks.
#
# For each submodule in local/sources/, fetches upstream and reports:
#   - Commits behind upstream (new upstream commits we don't have)
#   - Commits ahead of upstream (our Red Bear patches)
#   - Upstream HEAD date vs our HEAD date
#
# Exits 1 if any fork is behind upstream beyond the threshold.
#
# Usage:
#   ./local/scripts/check-fork-drift.sh                    # Report all
#   ./local/scripts/check-fork-drift.sh --threshold=20     # Fail if any fork >20 behind
#   ./local/scripts/check-fork-drift.sh --fetch-depth=100  # Deeper fetch (default: 200)
#   ./local/scripts/check-fork-drift.sh --no-fetch         # Skip network fetch (use cached refs)
#   ./local/scripts/check-fork-drift.sh --json             Machine-readable output
#   ./local/scripts/check-fork-drift.sh --quiet            Only print violations

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"

THRESHOLD=10
FETCH_DEPTH=200
NO_FETCH=0
JSON=0
QUIET=0

while [[ $# -gt 0 ]]; do
    case "$1" in
        --threshold=*)   THRESHOLD="${1#*=}" ;;
        --fetch-depth=*) FETCH_DEPTH="${1#*=}" ;;
        --no-fetch)      NO_FETCH=1 ;;
        --json)          JSON=1 ;;
        --quiet)         QUIET=1 ;;
        -h|--help)
            echo "Usage: $0 [--threshold=N] [--fetch-depth=N] [--no-fetch] [--json] [--quiet]"
            exit 0
            ;;
        *) echo "Unknown: $1" >&2; exit 1 ;;
    esac
    shift
done

cd "$PROJECT_ROOT"

# Submodules that have upstream remotes
declare -a FORKS=()
declare -A FORK_PATHS
while IFS= read -r line; do
    name=$(basename "$line")
    FORKS+=("$name")
    FORK_PATHS["$name"]="$line"
done < <(find local/sources -maxdepth 1 -mindepth 1 -type d -o -type l 2>/dev/null | sort)

if [[ ${#FORKS[@]} -eq 0 ]]; then
    echo "No local forks found under local/sources/" >&2
    exit 0
fi

VIOLATIONS=0
declare -a JSON_LINES=()

if [[ "$JSON" -eq 0 && "$QUIET" -eq 0 ]]; then
    printf "%-16s  %-8s  %-8s  %-12s  %-12s  %s\n" "FORK" "BEHIND" "AHEAD" "UPSTREAM" "OUR_HEAD" "STATUS"
    printf "%-16s  %-8s  %-8s  %-12s  %-12s  %s\n" "----" "-------" "------" "--------" "--------" "------"
fi

for fork in "${FORKS[@]}"; do
    fork_dir="${FORK_PATHS[$fork]}"
    if [[ ! -d "$fork_dir/.git" ]]; then
        continue
    fi

    upstream_remote=$(cd "$fork_dir" && git remote get-url upstream 2>/dev/null || true)
    if [[ -z "$upstream_remote" ]]; then
        continue
    fi

    # Determine upstream branch (master or main)
    upstream_branch="master"
    if ! (cd "$fork_dir" && git rev-parse --verify upstream/master >/dev/null 2>&1); then
        if (cd "$fork_dir" && git rev-parse --verify upstream/main >/dev/null 2>&1); then
            upstream_branch="main"
        else
            # Need to fetch first
            if [[ "$NO_FETCH" -eq 0 ]]; then
                (cd "$fork_dir" && git fetch upstream --depth="$FETCH_DEPTH" --quiet 2>/dev/null) || true
            fi
            if (cd "$fork_dir" && git rev-parse --verify upstream/master >/dev/null 2>&1); then
                upstream_branch="master"
            elif (cd "$fork_dir" && git rev-parse --verify upstream/main >/dev/null 2>&1); then
                upstream_branch="main"
            else
                continue
            fi
        fi
    fi

    # Fetch if needed
    if [[ "$NO_FETCH" -eq 0 ]]; then
        (cd "$fork_dir" && git fetch upstream --depth="$FETCH_DEPTH" --quiet 2>/dev/null) || true
    fi

    ref="upstream/$upstream_branch"
    behind=$(cd "$fork_dir" && git log --oneline "HEAD..$ref" 2>/dev/null | wc -l)
    ahead=$(cd "$fork_dir" && git log --oneline "$ref..HEAD" 2>/dev/null | wc -l)
    upstream_sha=$(cd "$fork_dir" && git rev-parse --short "$ref" 2>/dev/null || echo "?")
    our_sha=$(cd "$fork_dir" && git rev-parse --short HEAD 2>/dev/null || echo "?")
    upstream_date=$(cd "$fork_dir" && git log -1 --format='%ci' "$ref" 2>/dev/null | cut -d' ' -f1 || echo "?")
    our_date=$(cd "$fork_dir" && git log -1 --format='%ci' HEAD 2>/dev/null | cut -d' ' -f1 || echo "?")

    status="OK"
    if [[ "$behind" -gt "$THRESHOLD" ]]; then
        status="DRIFT"
        VIOLATIONS=$((VIOLATIONS + 1))
    elif [[ "$behind" -gt 0 ]]; then
        status="MINOR"
    fi

    if [[ "$JSON" -eq 1 ]]; then
        json_line=$(printf '{"fork":"%s","behind":%d,"ahead":%d,"upstream_sha":"%s","our_sha":"%s","upstream_date":"%s","our_date":"%s","status":"%s"}' \
            "$fork" "$behind" "$ahead" "$upstream_sha" "$our_sha" "$upstream_date" "$our_date" "$status")
        JSON_LINES+=("$json_line")
    elif [[ "$QUIET" -eq 0 ]] || [[ "$status" != "OK" ]]; then
        if [[ "$status" == "DRIFT" ]]; then
            printf "%-16s  \033[1;31m%-8s\033[0m  %-8s  %-12s  %-12s  %s\n" "$fork" "$behind" "$ahead" "$upstream_sha" "$our_sha" "$status"
        elif [[ "$status" == "MINOR" ]]; then
            printf "%-16s  \033[1;33m%-8s\033[0m  %-8s  %-12s  %-12s  %s\n" "$fork" "$behind" "$ahead" "$upstream_sha" "$our_sha" "$status"
        else
            printf "%-16s  \033[1;32m%-8s\033[0m  %-8s  %-12s  %-12s  %s\n" "$fork" "$behind" "$ahead" "$upstream_sha" "$our_sha" "$status"
        fi
    fi
done

if [[ "$JSON" -eq 1 ]]; then
    echo "["
    for i in "${!JSON_LINES[@]}"; do
        if [[ $i -lt $((${#JSON_LINES[@]} - 1)) ]]; then
            echo "  ${JSON_LINES[$i]},"
        else
            echo "  ${JSON_LINES[$i]}"
        fi
    done
    echo "]"
else
    echo ""
    if [[ "$VIOLATIONS" -gt 0 ]]; then
        echo -e "\033[1;31mDRIFT DETECTED: $VIOLATIONS fork(s) exceed threshold ($THRESHOLD commits behind upstream).\033[0m"
        echo ""
        echo "To upgrade forks to latest upstream:"
        echo "  ./local/scripts/upgrade-forks.sh"
        echo ""
        echo "To suppress this check in builds:"
        echo "  REDBEAR_SKIP_DRIFT_CHECK=1"
    else
        echo -e "\033[1;32mAll forks within drift threshold ($THRESHOLD commits).\033[0m"
    fi
fi

if [[ "$VIOLATIONS" -gt 0 ]]; then
    exit 1
fi
exit 0