#!/usr/bin/env bash
#
# CascadingDev Pre-commit Hook
# =============================
# This hook orchestrates AI-powered automation during git commits.
#
# What it does:
#   1. Creates companion summary files (.sum.md) for discussion files
#   2. Validates that discussion files are append-only (no deletions)
#   3. Runs automation/runner.py to generate AI-powered outputs
#   4. Runs automation/workflow.py to update vote summaries
#
# Safety: Exits on errors to prevent broken commits
set -euo pipefail

# Navigate to git repository root so all file paths work correctly
# regardless of where the user ran the commit command
ROOT="$(git rev-parse --show-toplevel 2>/dev/null || echo ".")"
cd "$ROOT"

# ============================================================================
# FUNCTION: check_append_only_discussion
# ============================================================================
# Validates that changes to discussion files only add content (no deletions).
#
# Discussion files are append-only to maintain conversation history.
# YAML header fields (status, timestamps, etc.) are allowed to change.
#
# Args:
#   $1 - Path to discussion file (e.g., "Docs/features/FR_*/discussions/*.discussion.md")
#
# Returns:
#   0 if valid (append-only or header changes only)
#   1 if invalid (deletions detected in body content)
#
# Note: This is a basic implementation using regex. A more robust version
#       would parse YAML front matter and validate append-only at the line level.
# ============================================================================
check_append_only_discussion() {
  local disc_file="$1"
  local diff_output

  # Get the staged diff for this file
  diff_output=$(git diff --cached "$disc_file")

  # Look for deletion lines (lines starting with "-" but not "---" file markers)
  # If we find any, the user may have deleted existing content
  if echo "$diff_output" | grep -E "^-[^-]" | grep -Ev "^--- a/" | grep -Ev "^\+\+\+ b/"; then
    echo >&2 "[pre-commit] Error: Deletions or modifications detected in existing lines of $disc_file."
    echo >&2 "           Discussion files must be append-only, except for allowed header fields."
    return 1
  fi

  # Check for modifications to YAML header fields
  # These are allowed (e.g., updating status: OPEN → READY_FOR_IMPLEMENTATION)
  # A more robust check would parse YAML front matter instead of using regex
  local header_modified=0
  if echo "$diff_output" | grep -E "^[-+]" | grep -E "^(status|created|updated|feature_id|stage_id):" > /dev/null; then
    header_modified=1
  fi

  # If there are additions and no body deletions, we're good
  # This assumes additions are at the end (append-only)
  if echo "$diff_output" | grep -E "^\+[^+]" | grep -Ev "^\+\+\+ b/" > /dev/null && [ "$header_modified" -eq 0 ]; then
    : # Valid: additions only (append-only pattern)
  fi

  return 0
}

# ============================================================================
# FUNCTION: ensure_summary
# ============================================================================
# Creates a companion summary file (.sum.md) for a discussion file if missing.
#
# Summary files provide structured views of discussions:
#   - Vote counts and latest votes per participant
#   - Action items, questions, decisions
#   - Timeline of major updates
#
# The Python automation (workflow.py) updates these files, but it expects
# them to already exist. This function ensures the initial template is created.
#
# Args:
#   $1 - Path to discussion file (e.g., "feature.discussion.md")
#
# Creates:
#   - {discussion}.sum.md (e.g., "feature.discussion.sum.md")
#   - Auto-stages the new file for inclusion in the commit
#
# Template location: assets/templates/feature.discussion.sum.md
# ============================================================================
ensure_summary() {
  local disc="$1"
  local dir; dir="$(dirname "$disc")"
  local sum="$dir/$(basename "$disc" .md).sum.md"
  local template_path="assets/templates/feature.discussion.sum.md"

  # Only create if it doesn't exist
  if [ ! -f "$sum" ]; then
    # Copy template content to the summary file
    cat "$template_path" > "$sum"

    # Auto-stage so it's included in this commit
    git add "$sum"

    echo >&2 "[pre-commit] Created summary file: $sum"
  fi
}

# ============================================================================
# STEP 1: Collect Staged Files
# ============================================================================
# Get all files staged for commit (Added or Modified only)
# Exit early if there's nothing to process
mapfile -t STAGED < <(git diff --cached --name-only --diff-filter=AM || true)
[ "${#STAGED[@]}" -eq 0 ] && exit 0

# ============================================================================
# STEP 2: Process Discussion Files
# ============================================================================
# For each staged discussion file:
#   1. Ensure companion .sum.md file exists (create from template if needed)
#   2. Validate append-only constraint (no deletions to conversation history)
#
# Discussion file pattern: Docs/features/FR_*/discussions/*.discussion.md
# ============================================================================
for f in "${STAGED[@]}"; do
  case "$f" in
    Docs/features/*/discussions/*.discussion.md)
      # Create .sum.md companion file if it doesn't exist
      ensure_summary "$f"

      # Validate append-only constraint
      if ! check_append_only_discussion "$f"; then
        exit 1 # Abort commit if deletions detected
      fi
      ;;
  esac
done

# ============================================================================
# STEP 3: Run AI Automation (runner.py)
# ============================================================================
# The runner processes staged files according to .ai-rules.yml configuration:
#   - Reads staged file diffs
#   - Generates AI prompts with context
#   - Calls Claude API to generate patches
#   - Applies patches to output files
#   - Auto-stages generated files
#
# Examples:
#   - request.md → generates feature.discussion.md (initial AI comment + vote)
#   - feature.discussion.md → may update implementation.discussion.md
#
# Exit codes:
#   - 0: Success (or no rules matched, or graceful error handling)
#   - 1: Fatal error (malformed YAML, missing dependencies, etc.)
#
# Debug artifacts: .git/ai-rules-debug/*.{raw.out,clean.diff,sanitized.diff,final.diff}
# ============================================================================
if [ -f "automation/runner.py" ]; then
  if ! python3 -m automation.runner; then
    echo "[pre-commit] automation.runner failed" >&2
    exit 1
  fi
fi

# ============================================================================
# STEP 4: Run Workflow Automation (workflow.py)
# ============================================================================
# The workflow parses discussion files and updates summary files:
#   - Extracts VOTE: lines (READY, CHANGES, REJECT)
#   - Counts votes per participant (latest vote wins)
#   - Extracts questions, action items, decisions (Q:, TODO:, DECISION:)
#   - Updates .sum.md files with structured data
#   - Auto-stages updated summary files
#
# This runs AFTER runner.py so it can process any discussion files that
# were just generated by the AI automation.
#
# Exit behavior: Always returns 0 (|| true) so vote tracking never blocks commits.
#                This is intentional - vote summaries are informational only.
# ============================================================================
if [ -x "automation/workflow.py" ]; then
  python3 automation/workflow.py --status || true
fi

# ============================================================================
# Success - Allow Commit to Proceed
# ============================================================================
exit 0