#!/usr/bin/env sh
set -eu

# Sync standards snapshot to project root.
# - Copies <snapshot>/.agents/<AGENTS_NS> -> <project-root>/.agents/<AGENTS_NS>
# - Updates <project-root>/.gitattributes (managed block by default)
# Existing targets are backed up before overwrite.
#
# Multi rulesets:
#   sh .../sync_standards.sh tsl cpp
#   sh .../sync_standards.sh --langs tsl,cpp
# Notes:
# - When syncing multiple rulesets, .gitattributes is synced only once (first ruleset).

SCRIPT_DIR="$(CDPATH= cd -- "$(dirname -- "$0")" && pwd -P)"
SRC="$(CDPATH= cd -- "$SCRIPT_DIR/.." && pwd -P)"
ROOT="$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel 2>/dev/null || pwd)"
ROOT="$(CDPATH= cd -- "$ROOT" && pwd -P)"
AGENTS_SRC_ROOT="$SRC/.agents"
GITATTR_SRC="$SRC/.gitattributes"

if [ ! -d "$AGENTS_SRC_ROOT" ]; then
  echo "ERROR: Standards snapshot not found at $AGENTS_SRC_ROOT" >&2
  echo "Run: git subtree add --prefix docs/standards/playbook <standards-url> <branch> --squash" >&2
  exit 1
fi

timestamp="$(date +%Y%m%d%H%M%S 2>/dev/null || echo bak)"

if [ "$SRC" = "$ROOT" ]; then
  echo "Skip: snapshot root equals project root."
  echo "Done."
  exit 0
fi

# Parse multi rulesets only on the outer invocation.
if [ "${SYNC_STANDARDS_INNER:-}" != "1" ]; then
  langs=""
  if [ "${1:-}" = "--langs" ]; then
    langs="${2:-}"
    shift 2
  fi
  if [ -z "${langs:-}" ] && [ "$#" -gt 0 ]; then
    langs="$*"
  fi
  if [ -n "${langs:-}" ]; then
    sync_mode_first="${SYNC_GITATTR_MODE:-block}"

    first=1
    old_ifs="${IFS}"
    IFS=', '
    set -- $langs
    IFS="${old_ifs}"

    for ns in "$@"; do
      [ -n "$ns" ] || continue
      if [ "$first" -eq 1 ]; then
        first=0
        SYNC_STANDARDS_INNER=1 AGENTS_NS="$ns" SYNC_GITATTR_MODE="$sync_mode_first" sh "$0"
      else
        SYNC_STANDARDS_INNER=1 AGENTS_NS="$ns" SYNC_GITATTR_MODE=skip sh "$0"
      fi
    done
    exit 0
  fi
fi

: "${AGENTS_NS:=tsl}"
case "$AGENTS_NS" in
  ""|*/*|*\\*|*..*)
    echo "ERROR: invalid AGENTS_NS=$AGENTS_NS" >&2
    exit 1
    ;;
esac

AGENTS_SRC="$AGENTS_SRC_ROOT/$AGENTS_NS"
if [ ! -d "$AGENTS_SRC" ]; then
  # Backward-compatible fallback: older snapshots used <snapshot>/.agents/* directly.
  if [ -f "$AGENTS_SRC_ROOT/index.md" ] && [ -f "$AGENTS_SRC_ROOT/auth.md" ]; then
    AGENTS_SRC="$AGENTS_SRC_ROOT"
  else
    echo "ERROR: agents ruleset not found: $AGENTS_SRC" >&2
    echo "Hint: set AGENTS_NS to one of the subdirs under $AGENTS_SRC_ROOT (e.g. tsl/cpp)." >&2
    exit 1
  fi
fi

AGENTS_ROOT="$ROOT/.agents"
AGENTS_DST="$AGENTS_ROOT/$AGENTS_NS"
mkdir -p "$AGENTS_ROOT"

if [ -e "$AGENTS_DST" ]; then
  mv "$AGENTS_DST" "$AGENTS_ROOT/$AGENTS_NS.bak.$timestamp"
  echo "Backed up existing $AGENTS_NS agents -> $AGENTS_NS.bak.$timestamp"
fi

cp -R "$AGENTS_SRC" "$AGENTS_DST"
echo "Synced .agents/$AGENTS_NS from standards."

AGENTS_INDEX="$AGENTS_ROOT/index.md"
if [ ! -f "$AGENTS_INDEX" ]; then
  cat >"$AGENTS_INDEX" <<'EOF'
# .agents（多语言）

本目录用于存放仓库级/语言级的代理规则集。

建议约定：

- `.agents/tsl/`：TSL 相关规则集（由 `sync_standards.*` 同步；适用于 `.tsl`/`.tsf`）
- `.agents/cpp/`：C++ 相关规则集（由 `sync_standards.*` 同步；适用于 C++23/Modules）
- `.agents/python/` 等：其他语言的规则集（按需增加）

规则发生冲突时，建议以“更靠近代码的目录规则更具体”为准。

入口建议从：

- `.agents/tsl/index.md`（TSL 规则集入口）
- `.agents/cpp/index.md`（C++ 规则集入口）
- `docs/standards/playbook/docs/`（人类开发规范快照：`tsl/`、`cpp/`、`python/`、`common/`）
EOF
  echo "Created .agents/index.md"
fi

echo "Synced agents ruleset to $AGENTS_DST."

GITATTR_DST="$ROOT/.gitattributes"
if [ -f "$GITATTR_SRC" ]; then
  : "${SYNC_GITATTR_MODE:=block}"
  case "$SYNC_GITATTR_MODE" in
    skip)
      echo "Skip: .gitattributes sync (SYNC_GITATTR_MODE=skip)."
      ;;
    overwrite)
      if [ "$(CDPATH= cd -- "$(dirname -- "$GITATTR_SRC")" && pwd -P)/$(basename -- "$GITATTR_SRC")" = "$GITATTR_DST" ]; then
        echo "Skip: .gitattributes source equals destination."
      else
        if [ -e "$GITATTR_DST" ]; then
          mv "$GITATTR_DST" "$ROOT/.gitattributes.bak.$timestamp"
          echo "Backed up existing .gitattributes -> .gitattributes.bak.$timestamp"
        fi
        cp "$GITATTR_SRC" "$GITATTR_DST"
        echo "Synced .gitattributes from standards (overwrite)."
      fi
      ;;
    block)
      begin="# BEGIN playbook .gitattributes"
      end="# END playbook .gitattributes"
      begin_old="# BEGIN tsl-playbook .gitattributes"
      end_old="# END tsl-playbook .gitattributes"

      if [ -e "$GITATTR_DST" ]; then
        mv "$GITATTR_DST" "$ROOT/.gitattributes.bak.$timestamp"
        echo "Backed up existing .gitattributes -> .gitattributes.bak.$timestamp"
      fi

      tmp="${GITATTR_DST}.tmp.${timestamp}"
      if [ -f "$ROOT/.gitattributes.bak.$timestamp" ]; then
        src_dst="$ROOT/.gitattributes.bak.$timestamp"
      else
        src_dst=""
      fi

      if [ -n "$src_dst" ]; then
        awk -v begin="$begin" -v end="$end" -v begin_old="$begin_old" -v end_old="$end_old" -v src="$GITATTR_SRC" '
          function emit_src() {
            print begin
            while ((getline line < src) > 0) print line
            close(src)
            print end
          }
          BEGIN { in_block=0; done=0 }
          $0 == begin || $0 == begin_old { in_block=1; if (!done) { emit_src(); done=1 } ; next }
          $0 == end   || $0 == end_old   { in_block=0; next }
          !in_block   { print }
          END {
            if (!done) {
              if (NR > 0) print ""
              emit_src()
            }
          }
        ' "$src_dst" >"$tmp"
      else
        {
          printf "%s\n" "$begin"
          cat "$GITATTR_SRC"
          printf "\n%s\n" "$end"
        } >"$tmp"
      fi

      mv "$tmp" "$GITATTR_DST"
      echo "Updated .gitattributes from standards (managed block)."
      ;;
    *)
      echo "ERROR: invalid SYNC_GITATTR_MODE=$SYNC_GITATTR_MODE (use block|overwrite|skip)" >&2
      exit 1
      ;;
  esac
fi

echo "Done."