#!/usr/bin/env bash
# =============================================================================
# lib/lint.sh
# Validation logic for Knowledge Genome files.
# =============================================================================

# Valid values for the 'type' frontmatter field.
# Must stay in sync with the type list in templates/agents-genome.md.
VALID_TYPES=("source" "entity" "concept" "query" "conflict" "private" "index" "log")

# ---------------------------------------------------------------------------
# lint_markdown_file <file> <genome_name>
# Validates YAML frontmatter: delimiters, mandatory fields, domain, type value.
# Returns the number of errors found.
# ---------------------------------------------------------------------------
lint_markdown_file() {
  local file="$1"
  local genome_name="$2"
  local errors=0

  # 1. Check frontmatter delimiters
  if [[ $(head -n 1 "$file") != "---" ]]; then
    warn "Missing frontmatter start (---) in: $file"
    errors=$((errors + 1))
  fi

  # 2. Check mandatory fields
  local mandatory_fields=("title:" "type:" "domain:" "maturity:" "last_updated:")
  for field in "${mandatory_fields[@]}"; do
    if ! grep -q "^${field}" "$file"; then
      warn "Missing mandatory field '${field}' in: $file"
      errors=$((errors + 1))
    fi
  done

  # 3. Check domain matches genome name
  if grep -q "^domain:" "$file" && ! grep -q "^domain: ${genome_name}" "$file"; then
    warn "Domain mismatch in $file (expected '${genome_name}')"
    errors=$((errors + 1))
  fi

  # 4. Validate type value against allowed list
  local type_errors
  check_valid_type "$file"
  type_errors=$?
  errors=$((errors + type_errors))

  return $errors
}

# ---------------------------------------------------------------------------
# check_valid_type <file>
# Verifies that the 'type' field contains a value from VALID_TYPES.
# Returns 1 if invalid, 0 if valid or field absent (absence caught by lint_markdown_file).
# ---------------------------------------------------------------------------
check_valid_type() {
  local file="$1"

  local type_value
  type_value=$(grep "^type:" "$file" | head -1 | sed 's/^type:[[:space:]]*//' | tr -d '"')

  [[ -z "$type_value" ]] && return 0   # absence is caught upstream

  local valid=0
  for t in "${VALID_TYPES[@]}"; do
    [[ "$type_value" == "$t" ]] && valid=1 && break
  done

  if [[ $valid -eq 0 ]]; then
    warn "Invalid type value '${type_value}' in: $file"
    warn "  Valid types: ${VALID_TYPES[*]}"
    return 1
  fi

  return 0
}

# ---------------------------------------------------------------------------
# check_privacy_consistency <file>
# Ensures files in private/ directories carry 'private: true'.
# Warns if a public file is incorrectly marked private.
# ---------------------------------------------------------------------------
check_privacy_consistency() {
  local file="$1"
  local errors=0

  if [[ "$file" == *"/private/"* ]]; then
    if ! grep -q "^private: true" "$file"; then
      error "Privacy leak: $file is in a private/ directory but lacks 'private: true'."
      errors=$((errors + 1))
    fi
  else
    if grep -q "^private: true" "$file"; then
      warn "Metadata mismatch: $file is marked 'private: true' but is in a public directory."
    fi
  fi

  return $errors
}

# ---------------------------------------------------------------------------
# check_knowledge_decay <file>
# Reads 'maturity' and 'last_updated' from frontmatter and compares against
# the staleness thresholds defined in agents-genome.md:
#   maturity: stable  → flag if last_updated > 180 days ago
#   maturity: draft   → flag if last_updated > 90 days ago
#
# Returns 1 if the file is stale, 0 otherwise.
# Silently skips files with missing or unparseable date fields.
# ---------------------------------------------------------------------------
check_knowledge_decay() {
  local file="$1"

  local last_updated maturity
  last_updated=$(grep "^last_updated:" "$file" | head -1 | sed 's/^last_updated:[[:space:]]*//' | tr -d '"')
  maturity=$(grep "^maturity:" "$file" | head -1 | sed 's/^maturity:[[:space:]]*//' | tr -d '"')

  # Skip if either field is absent or maturity is not decay-trackable
  [[ -z "$last_updated" || -z "$maturity" ]] && return 0
  [[ "$maturity" != "stable" && "$maturity" != "draft" ]] && return 0

  # Parse date — handle both GNU date (Linux) and BSD date (macOS)
  local updated_ts
  if date --version &>/dev/null 2>&1; then
    # GNU date
    updated_ts=$(date -d "$last_updated" +%s 2>/dev/null)
  else
    # BSD date (macOS)
    updated_ts=$(date -j -f "%Y-%m-%d" "$last_updated" +%s 2>/dev/null)
  fi

  [[ -z "$updated_ts" ]] && return 0   # unparseable date — skip silently

  local now days_old threshold
  now=$(date +%s)
  days_old=$(( (now - updated_ts) / 86400 ))

  case "$maturity" in
    stable) threshold=180 ;;
    draft)  threshold=90  ;;
  esac

  if [[ $days_old -gt $threshold ]]; then
    warn "STALE: $file"
    warn "  maturity: ${maturity} | last_updated: ${last_updated} | ${days_old} days ago (threshold: ${threshold})"
    return 1
  fi

  return 0
}

# ---------------------------------------------------------------------------
# check_broken_links <file>
# Basic check for internal [[wikilinks]] that cannot be resolved locally.
# Only emits warnings — cross-genome links may legitimately not resolve here.
# ---------------------------------------------------------------------------
check_broken_links() {
  local file="$1"
  local base_dir
  base_dir=$(dirname "$file")

  # Extract link targets, stripping aliases: [[Link|Alias]] -> Link
  local links
  links=$(grep -oP '\[\[\K[^\]]+' "$file" 2>/dev/null | cut -d'|' -f1)

  for link in $links; do
    local target="$link"
    [[ "$target" != *.md ]] && target="${target}.md"

    if [[ ! -f "${base_dir}/${target}" && ! -f "${base_dir}/../${target}" ]]; then
      warn "Potential broken link: [[$link]] in $file"
    fi
  done
}