#!/bin/bash
# -----------------------------------------------------------------------------------------------
# --------------------------------- Backup Verify ----------------------------------------------
# -----------------------------------------------------------------------------------------------
# Verifies the rsync mirror is healthy by comparing random file samples between
# local and remote servers using MD5 checksums.
#
# Randomly samples BACKUP_VERIFY_SAMPLE files per share, computes checksums locally,
# then computes the same checksums on the remote via SSH and compares results.
#
# Results per file:
#   MATCH   — checksums identical, file is correctly mirrored
#   MISMATCH — file exists on both but checksums differ — sync may have failed
#   MISSING  — file exists locally but not on remote — not yet synced or deleted
#
# Silent when all files match. Notifies on any mismatch or missing file.
# Uses existing SSH keys — no additional configuration needed beyond share list.
#
# All configuration in Master.conf under Backup Verify section.
# Supports --dry-run to show what would be checked without running checksums.
# -----------------------------------------------------------------------------------------------

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

source "$SCRIPT_DIR/../Master.conf"
source "$SCRIPT_DIR/../common.sh"

parse_args "$@"

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_GEAR Setup ━━━
# -----------------------------------------------------------------------------------------------
echo ""
echo "━━━ $ICON_GEAR Setup ━━━"

detect_hosts
resolve_remote_ip

# Use BACKUP_VERIFY_SHARES if defined, fall back to DAILY_SYNC_SHARES
if [[ ${#BACKUP_VERIFY_SHARES[@]} -gt 0 ]]; then
    VERIFY_SHARES=("${BACKUP_VERIFY_SHARES[@]}")
    info "Using BACKUP_VERIFY_SHARES (${#VERIFY_SHARES[@]} shares)"
else
    VERIFY_SHARES=("${DAILY_SYNC_SHARES[@]}")
    info "BACKUP_VERIFY_SHARES not set — using DAILY_SYNC_SHARES (${#VERIFY_SHARES[@]} shares)"
fi

if [[ ${#VERIFY_SHARES[@]} -eq 0 ]]; then
    warn "No shares configured — nothing to verify"
    exit 0
fi

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_SUMMARY Status ━━━
# -----------------------------------------------------------------------------------------------
if [[ "$SHOW_STATUS" == true ]]; then
    echo ""
    echo "━━━━━ $ICON_SUMMARY STATUS ━━━━━"
    echo "$ICON_VERIFY  Shares:     ${#VERIFY_SHARES[@]}"
    echo "$ICON_VERIFY  Sample:     $BACKUP_VERIFY_SAMPLE files per share"
    echo "$ICON_VERIFY  Min size:   $BACKUP_VERIFY_MIN_SIZE"
    echo "$ICON_HOST    Remote:     $REMOTE_SERVER_NAME ($REMOTE_SERVER)"
    echo "$ICON_GEAR    Dry Run:    $DRY_RUN"
    echo "━━━━━━━━━━━━━━━━━━━━━━━"
    exit 0
fi

[[ "$DRY_RUN" == true ]] && warn "DRY RUN — showing sample selection only, no checksums computed"

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_VERIFY Backup Verification ━━━
# -----------------------------------------------------------------------------------------------
echo ""
echo "━━━ $ICON_VERIFY Backup Verification — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
echo "$ICON_HOST  Remote: $REMOTE_SERVER_NAME ($REMOTE_SERVER)"
echo "$ICON_VERIFY Sample: $BACKUP_VERIFY_SAMPLE files per share (min size: $BACKUP_VERIFY_MIN_SIZE)"
echo ""

START=$(date +%s)
TOTAL_CHECKED=0
TOTAL_MATCH=0
TOTAL_MISMATCH=0
TOTAL_MISSING=0
SHARES_WITH_ISSUES=()

for share in "${VERIFY_SHARES[@]}"; do
    SHARE_NAME=$(basename "$share")
    echo "━━━ $ICON_VERIFY $SHARE_NAME ━━━"

    if [[ ! -d "$share" ]]; then
        warn "$SHARE_NAME not found locally — skipping"
        echo ""
        continue
    fi

    # Find files above minimum size and randomly sample
    SAMPLE_FILES=$(find "$share" -type f -size +"$BACKUP_VERIFY_MIN_SIZE" 2>/dev/null | \
        shuf | head -n "$BACKUP_VERIFY_SAMPLE")

    SAMPLE_COUNT=$(echo "$SAMPLE_FILES" | grep -c "." 2>/dev/null || echo 0)

    if [[ "$SAMPLE_COUNT" -eq 0 ]]; then
        info "No files found above $BACKUP_VERIFY_MIN_SIZE — skipping"
        echo ""
        continue
    fi

    info "Sampled $SAMPLE_COUNT files"

    if [[ "$DRY_RUN" == true ]]; then
        echo "$SAMPLE_FILES" | while IFS= read -r f; do
            warn "DRY RUN — would check: $(basename "$f")"
        done
        echo ""
        continue
    fi

    SHARE_MISMATCH=0
    SHARE_MISSING=0
    SHARE_MATCH=0

    while IFS= read -r local_file; do
        [[ -z "$local_file" ]] && continue

        # Compute local checksum
        local_md5=$(md5sum "$local_file" 2>/dev/null | awk '{print $1}')

        if [[ -z "$local_md5" ]]; then
            warn "Could not checksum: $local_file — skipping"
            continue
        fi

        # Compute remote checksum via SSH
        remote_md5=$(ssh -i "$SSH_KEY" -o ConnectTimeout=10 root@"$REMOTE_SERVER" \
            "md5sum '$local_file' 2>/dev/null | awk '{print \$1}'" 2>/dev/null)

        ((TOTAL_CHECKED++))

        if [[ -z "$remote_md5" ]]; then
            warn "$ICON_ERROR MISSING: $(basename "$local_file")"
            ((SHARE_MISSING++))
            ((TOTAL_MISSING++))
        elif [[ "$local_md5" == "$remote_md5" ]]; then
            log "MATCH: $(basename "$local_file")"
            ((SHARE_MATCH++))
            ((TOTAL_MATCH++))
        else
            error "$ICON_ERROR MISMATCH: $(basename "$local_file")"
            ((SHARE_MISMATCH++))
            ((TOTAL_MISMATCH++))
        fi

    done <<< "$SAMPLE_FILES"

    echo "  $ICON_SUCCESS Match: $SHARE_MATCH  $ICON_WARN Missing: $SHARE_MISSING  $ICON_ERROR Mismatch: $SHARE_MISMATCH"

    if [[ "$SHARE_MISMATCH" -gt 0 || "$SHARE_MISSING" -gt 0 ]]; then
        SHARES_WITH_ISSUES+=("$SHARE_NAME")
    fi

    echo ""
done

END=$(date +%s)

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_SUMMARY Summary ━━━
# -----------------------------------------------------------------------------------------------
echo "━━━━━ $ICON_SUMMARY BACKUP VERIFY SUMMARY ━━━━━"
echo "$ICON_HOST    Remote:    $REMOTE_SERVER_NAME"
echo "$ICON_VERIFY  Checked:   $TOTAL_CHECKED files"
echo "$ICON_SUCCESS Match:     $TOTAL_MATCH"
echo "$ICON_WARN    Missing:   $TOTAL_MISSING"
echo "$ICON_ERROR   Mismatch:  $TOTAL_MISMATCH"
echo "$ICON_TIME    Duration:  $(format_duration $((END - START)))"
echo ""

if [[ "$DRY_RUN" == true ]]; then
    echo "$ICON_WARN Status: DRY RUN — no checksums computed"
elif [[ "$TOTAL_MISMATCH" -gt 0 || "$TOTAL_MISSING" -gt 0 ]]; then
    echo "$ICON_ERROR Status: ISSUES FOUND — ${#SHARES_WITH_ISSUES[@]} share(s) need attention"
    notify "Backup verify failed on $(hostname) → $REMOTE_SERVER_NAME — mismatches: $TOTAL_MISMATCH missing: $TOTAL_MISSING — shares: ${SHARES_WITH_ISSUES[*]}" "Backup Verify" "warning"
else
    echo "$ICON_DONE Status: $ICON_SUCCESS ALL FILES MATCH"
    notify "Backup verify passed on $(hostname) → $REMOTE_SERVER_NAME — $TOTAL_CHECKED files checked across ${#VERIFY_SHARES[@]} shares" "Backup Verify" "normal"
fi
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"