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

SKILL_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
SKILL_ROOT="$(cd "$SKILL_DIR/.." && pwd)"
TEMPLATES_DIR="$SKILL_ROOT/assets/templates"

usage() {
  cat <<EOF
Usage: new-agent.sh <agent-name> <root>

Scaffold agent definition files for Claude Code and GitHub Copilot CLI.

Arguments:
  agent-name  Kebab-case agent identifier (e.g. code-reviewer, deploy-assistant).
  root        Root directory — determines scope:
                plugin scope  : root contains plugin.json
                               → creates <root>/agents/<name>.md
                               → creates <root>/agents/<name>.agent.md
                               → creates <root>/sources.md (if absent)
                project scope : root is a project directory (no plugin.json)
                               → creates <root>/.claude/agents/<name>.md
                               → creates <root>/.github/agents/<name>.agent.md
                user scope    : root is ~ (home directory)
                               → creates ~/.claude/agents/<name>.md
                               → creates ~/.copilot/agents/<name>.agent.md

              Each file is created only if it does not already exist (no-op per file).

Exit codes:
  0  Files created or already existed (no-op)
  1  Invalid arguments, missing root, or templates not found
EOF
}

if [[ "${1:-}" == "--help" || "${1:-}" == "-h" ]]; then
  usage
  exit 0
fi

if [[ $# -lt 2 ]]; then
  echo "Error: agent-name and root are required." >&2
  echo "" >&2
  usage >&2
  exit 1
fi

AGENT_NAME="$1"
ROOT="$2"

# Validate agent name format
if ! echo "$AGENT_NAME" | grep -qE '^[a-z0-9]+(-[a-z0-9]+)*$'; then
  echo "Error: agent-name must use lowercase letters, numbers, and hyphens only." >&2
  echo "       No leading, trailing, or consecutive hyphens." >&2
  echo "       Received: '$AGENT_NAME'" >&2
  exit 1
fi

# Validate templates directory
if [[ ! -d "$TEMPLATES_DIR" ]]; then
  echo "Error: templates directory not found at '$TEMPLATES_DIR'." >&2
  echo "       Run this script from its original location inside the agent-author skill." >&2
  exit 1
fi

# Expand tilde
ROOT="${ROOT/#\~/$HOME}"

# Validate root exists
if [[ ! -d "$ROOT" ]]; then
  echo "Error: root directory '$ROOT' does not exist." >&2
  exit 1
fi

# Detect scope
if [[ -f "$ROOT/plugin.json" || -f "$ROOT/.claude-plugin/plugin.json" || -f "$ROOT/.plugin/plugin.json" || -f "$ROOT/.github/plugin/plugin.json" ]]; then
  SCOPE="plugin"
elif [[ "$ROOT" == "$HOME" ]]; then
  SCOPE="user"
else
  SCOPE="project"
fi

# Determine file destinations
case "$SCOPE" in
  plugin)
    CC_DIR="$ROOT/agents"
    CP_DIR="$ROOT/agents"
    SOURCES_DIR="$ROOT"
    ;;
  project)
    CC_DIR="$ROOT/.claude/agents"
    CP_DIR="$ROOT/.github/agents"
    SOURCES_DIR=""
    ;;
  user)
    CC_DIR="$HOME/.claude/agents"
    CP_DIR="$HOME/.copilot/agents"
    SOURCES_DIR=""
    ;;
esac

CC_FILE="$CC_DIR/$AGENT_NAME.md"
CP_FILE="$CP_DIR/$AGENT_NAME.agent.md"

# Create directories
mkdir -p "$CC_DIR"
mkdir -p "$CP_DIR"

# Copy Claude Code template (no-op if exists)
created_any=false
if [[ -f "$CC_FILE" ]]; then
  echo "Skipping '$CC_FILE' — already exists." >&2
else
  sed "s/AGENT_NAME/$AGENT_NAME/g" "$TEMPLATES_DIR/claude-code.md" > "$CC_FILE"
  echo "Created: $CC_FILE" >&2
  created_any=true
fi

# Copy Copilot template (no-op if exists)
if [[ -f "$CP_FILE" ]]; then
  echo "Skipping '$CP_FILE' — already exists." >&2
else
  sed "s/AGENT_NAME/$AGENT_NAME/g" "$TEMPLATES_DIR/copilot.agent.md" > "$CP_FILE"
  echo "Created: $CP_FILE" >&2
  created_any=true
fi

# Create sources.md at plugin scope (no-op if exists)
if [[ -n "$SOURCES_DIR" ]]; then
  SOURCES_FILE="$SOURCES_DIR/sources.md"
  if [[ -f "$SOURCES_FILE" ]]; then
    echo "Skipping '$SOURCES_FILE' — already exists." >&2
  else
    cat > "$SOURCES_FILE" <<'SOURCES'
# Sources

<!-- List research sources that informed agents in this directory.
     Follow the format below. Only include entries with `extracted` status.
     Delete this file if no research sources informed these agents. -->

<!-- ## source-slug
- **URL:** <url>
- **Research doc:** <relative-path-to-upstream-research-sources-file>
- **Description:** <what this source covers>
- **Contributing files:** agents/<name>.md, agents/<name>.agent.md
- **Status:** `extracted` -->
SOURCES
    echo "Created: $SOURCES_FILE" >&2
    created_any=true
  fi
fi

if [[ "$created_any" == false ]]; then
  echo "All files already exist — nothing to do." >&2
else
  echo "" >&2
  echo "Scope: $SCOPE" >&2
  echo "" >&2
  echo "Next steps:" >&2
  echo "  1. Fill in $CC_FILE — replace all FILL IN: placeholders" >&2
  echo "  2. Fill in $CP_FILE — replace all FILL IN: placeholders" >&2
  if [[ -n "$SOURCES_DIR" ]]; then
    echo "  3. Populate $SOURCES_DIR/sources.md with research sources, or delete it" >&2
    echo "  4. Validate: check required fields (name, description, system prompt) in both files" >&2
  else
    echo "  3. Validate: check required fields (name, description, system prompt) in both files" >&2
  fi
fi