#!/usr/bin/env bash
set -euo pipefail

# Installs git hook blocks for validation into a target repository.
# Usage: setup-hooks.sh [TARGET_REPO]
#   TARGET_REPO — path to the git repo to configure (default: current directory)
# Idempotent: safe to re-run; always replaces each managed block with the current version.

SHELLCHECK_VERSION="0.10.0"
JQ_VERSION="1.7.1"
YQ_VERSION="4.44.3"
TOOL_INSTALL_DIR="${TOOL_INSTALL_DIR:-/usr/local/bin}"

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
TARGET="${1:-$(pwd)}"
MARKER="# managed by setup-hooks.sh"
END_MARKER="# end setup-hooks"

if [[ ! -d "$TARGET/.git" ]]; then
  echo "Error: $TARGET is not a git repository" >&2
  exit 1
fi

# --- Tool installation ---

_os() {
  case "$(uname -s)" in
    Linux)  echo "linux"  ;;
    Darwin) echo "darwin" ;;
    *) echo "Error: unsupported OS '$(uname -s)'" >&2; exit 1 ;;
  esac
}

_arch() {
  case "$(uname -m)" in
    x86_64)          echo "x86_64" ;;
    aarch64 | arm64) echo "aarch64" ;;
    *) echo "Error: unsupported architecture '$(uname -m)'" >&2; exit 1 ;;
  esac
}

install_shellcheck() {
  local os arch tarball url tmp_dir
  os="$(_os)"
  arch="$(_arch)"
  tarball="shellcheck-v${SHELLCHECK_VERSION}.${os}.${arch}.tar.xz"
  url="https://github.com/koalaman/shellcheck/releases/download/v${SHELLCHECK_VERSION}/${tarball}"
  tmp_dir="$(mktemp -d)"
  trap 'rm -rf "$tmp_dir"' RETURN
  echo "Installing shellcheck v${SHELLCHECK_VERSION}..."
  curl -fsSL "$url" -o "$tmp_dir/$tarball"
  tar -xJf "$tmp_dir/$tarball" -C "$tmp_dir" --strip-components=1
  install -m 755 "$tmp_dir/shellcheck" "$TOOL_INSTALL_DIR/shellcheck"
  echo "Installed: $TOOL_INSTALL_DIR/shellcheck"
}

install_jq() {
  local os arch binary url tmp_dir
  os="$(_os)"
  arch="$(_arch | sed 's/x86_64/amd64/; s/aarch64/arm64/')"
  [[ "$(_os)" == "darwin" ]] && os="macos"
  binary="jq-${os}-${arch}"
  url="https://github.com/jqlang/jq/releases/download/jq-${JQ_VERSION}/${binary}"
  tmp_dir="$(mktemp -d)"
  trap 'rm -rf "$tmp_dir"' RETURN
  echo "Installing jq v${JQ_VERSION}..."
  curl -fsSL "$url" -o "$tmp_dir/jq"
  install -m 755 "$tmp_dir/jq" "$TOOL_INSTALL_DIR/jq"
  echo "Installed: $TOOL_INSTALL_DIR/jq"
}

install_yq() {
  local os arch binary url tmp_dir
  os="$(_os)"
  arch="$(_arch | sed 's/x86_64/amd64/; s/aarch64/arm64/')"
  binary="yq_${os}_${arch}"
  url="https://github.com/mikefarah/yq/releases/download/v${YQ_VERSION}/${binary}"
  tmp_dir="$(mktemp -d)"
  trap 'rm -rf "$tmp_dir"' RETURN
  echo "Installing yq v${YQ_VERSION}..."
  curl -fsSL "$url" -o "$tmp_dir/yq"
  install -m 755 "$tmp_dir/yq" "$TOOL_INSTALL_DIR/yq"
  echo "Installed: $TOOL_INSTALL_DIR/yq"
}

ensure_tool() {
  local tool="$1"
  if ! command -v "$tool" &>/dev/null; then
    "install_${tool}"
  fi
}

ensure_tool shellcheck
ensure_tool jq
ensure_tool yq

# --- Marker-block helpers ---

write_block() {
  local hook_file="$1"
  local block_content="$2"

  if grep -qF "$MARKER" "$hook_file"; then
    awk -v start="$MARKER" -v end="$END_MARKER" '
      $0 == start { skip=1; next }
      skip && $0 == end { skip=0; next }
      !skip { print }
    ' "$hook_file" > "${hook_file}.tmp" && mv "${hook_file}.tmp" "$hook_file"
  fi

  printf '\n%s\n%s\n%s\n' "$MARKER" "$block_content" "$END_MARKER" >> "$hook_file"
  chmod +x "$hook_file"
}

ensure_hook() {
  local hook_file="$1"
  if [[ ! -f "$hook_file" ]]; then
    printf '#!/usr/bin/env bash\nset -euo pipefail\n' > "$hook_file"
    chmod +x "$hook_file"
  fi
}

# --- commit-msg: conventional commits ---

COMMIT_MSG_HOOK="$TARGET/.git/hooks/commit-msg"
ensure_hook "$COMMIT_MSG_HOOK"

commit_msg_block() {
  cat <<'BLOCK'
msg=$(cat "$1")
pattern='^(feat|fix|docs|chore|refactor|test|perf|ci|build|revert)(\(.+\))?!?: .+'
if ! echo "$msg" | grep -qE "$pattern"; then
  echo "ERROR: Commit message must follow Conventional Commits format." >&2
  echo "  Examples: feat: add login, fix(auth): correct token expiry, chore!: drop python dep" >&2
  exit 1
fi
BLOCK
}

write_block "$COMMIT_MSG_HOOK" "$(commit_msg_block)"
echo "Updated: $COMMIT_MSG_HOOK (conventional commits check)"

# --- pre-commit: shellcheck + jq/yq + SKILL.md frontmatter ---

PRE_COMMIT_HOOK="$TARGET/.git/hooks/pre-commit"
ensure_hook "$PRE_COMMIT_HOOK"

pre_commit_block() {
  cat <<'BLOCK'
staged=$(git diff --cached --name-only --diff-filter=ACM)

# shellcheck on staged .sh files
if command -v shellcheck &>/dev/null; then
  while IFS= read -r f; do
    [[ -f "$f" ]] && shellcheck "$f"
  done < <(echo "$staged" | grep '\.sh$' || true)
else
  echo "Warning: shellcheck not installed — shell script linting skipped" >&2
fi

# jq validation on staged .json files
if command -v jq &>/dev/null; then
  while IFS= read -r f; do
    [[ -f "$f" ]] && jq . "$f" > /dev/null
  done < <(echo "$staged" | grep '\.json$' || true)
else
  echo "Warning: jq not installed — JSON validation skipped" >&2
fi

# yq validation on staged .yaml/.yml files
if command -v yq &>/dev/null; then
  while IFS= read -r f; do
    [[ -f "$f" ]] && yq eval '.' "$f" > /dev/null
  done < <(echo "$staged" | grep -E '\.(yaml|yml)$' || true)
else
  echo "Warning: yq not installed — YAML validation skipped" >&2
fi

# SKILL.md frontmatter: must have name: and description:
while IFS= read -r f; do
  if [[ -f "$f" ]]; then
    if ! grep -q '^name:' "$f" || ! grep -q '^description' "$f"; then
      echo "ERROR: $f is missing required frontmatter fields (name: and description:)" >&2
      exit 1
    fi
  fi
done < <(echo "$staged" | grep 'SKILL\.md$' || true)
BLOCK
}

write_block "$PRE_COMMIT_HOOK" "$(pre_commit_block)"
echo "Updated: $PRE_COMMIT_HOOK (shellcheck + jq/yq + SKILL.md validation)"

# --- pre-push: test suite + manifest cross-reference ---

PRE_PUSH_HOOK="$TARGET/.git/hooks/pre-push"
ensure_hook "$PRE_PUSH_HOOK"

pre_push_block() {
  local script_dir="$SCRIPT_DIR"
  cat <<BLOCK
HOOKS_SCRIPT_DIR="$script_dir"
REPO_ROOT="\$(git rev-parse --show-toplevel)"

echo "Running test suite..."
bash "\$REPO_ROOT/tests/test-install.sh"
bash "\$REPO_ROOT/tests/test-governance-layer.sh"
bash "\$REPO_ROOT/tests/test-check-manifests.sh"
bash "\$REPO_ROOT/tests/test-setup-hooks.sh"

echo "Checking manifests..."
bash "\$HOOKS_SCRIPT_DIR/check-manifests.sh" "\$REPO_ROOT"
BLOCK
}

write_block "$PRE_PUSH_HOOK" "$(pre_push_block)"
echo "Updated: $PRE_PUSH_HOOK (test suite + manifest check)"

echo ""
echo "Done. Hooks installed in $TARGET/.git/hooks/"
echo "To skip on a single push: git push --no-verify"