#!/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 file(s) for Claude Code, GitHub Copilot CLI, and/or
vendor-neutral APM packages.

Arguments:
  agent-name  Kebab-case agent identifier (e.g. code-reviewer, deploy-assistant).
  root        Starting directory — scope is resolved by walking up from here:
                plugin/APM scope : nearest ancestor (at/above root) whose apm.yml
                                    has a top-level type: field (instructions,
                                    skill, hybrid, or prompts) — an apm.yml
                                    without type: is a marketplace-only manifest
                                    and is skipped, the walk continues upward
                               → creates <package-root>/.apm/agents/<name>.agent.md
                                 (single vendor-neutral file; apm compile copies
                                 its frontmatter verbatim to every target with no
                                 per-target field integrator, so the permitted
                                 field set is narrow — see the apm-agent-allowlist
                                 section of agent-audit's
                                 references/field-inventory.md and ADR-0016)
                               → creates <package-root>/sources.md (if absent)
                project scope    : no type:-bearing apm.yml found; root is a
                                    project directory
                               → creates <root>/.claude/agents/<name>.md
                               → creates <root>/.github/agents/<name>.agent.md
                user scope       : root is exactly ~ (home directory; checked
                                    directly, no walk-up)
                               → 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
ROOT="$(cd "$ROOT" && pwd)"

# True if apm_yml's top-level `type:` line names one of the four APM package
# types (instructions/skill/hybrid/prompts) — mirrors validate.sh's
# APM_TYPE_RE: an optional quote around the value must be closed by the
# *same* quote character (a mismatched or unterminated quote is rejected,
# not silently stripped), and the value must be followed by whitespace or
# end-of-line so `prompts-only` doesn't false-match on the `prompts` prefix.
# `|| [[ -n "$line" ]]` in the read condition also processes a final line
# that lacks a trailing newline, which `read` alone would otherwise skip.
is_apm_package_manifest() {
  local apm_yml="$1" line
  while IFS= read -r line || [[ -n "$line" ]]; do
    if [[ "$line" =~ ^type:[[:space:]]*(instructions|skill|hybrid|prompts)([[:space:]]|$) ]]; then
      return 0
    fi
    if [[ "$line" =~ ^type:[[:space:]]*([\"\'])(instructions|skill|hybrid|prompts)([\"\'])([[:space:]]|$) ]] \
       && [[ "${BASH_REMATCH[1]}" == "${BASH_REMATCH[3]}" ]]; then
      return 0
    fi
  done < "$apm_yml"
  return 1
}

# --- Walk-up package-root detection ---
#
# Mirrors agent-audit's validate.sh scope walk-up, with apm.yml + type: swapped
# in for the old plugin.json marker. Starting at ROOT, walk upward:
#   - an apm.yml with a top-level `type:` field marks an APM package root
#     (plugin/APM scope) — stop and return it.
#   - an apm.yml with no `type:` field is a marketplace-only manifest — skip
#     it, keep walking up.
#   - user scope is checked directly at $HOME, no walk-up (see usage text
#     above): ROOT itself being $HOME resolves to user scope, even if $HOME
#     is itself a .git-tracked dotfiles directory (checked before the .git
#     test below, so a dotfiles repo at $HOME can't shadow user scope).
#     Walking *up into* $HOME from a nested directory with no apm.yml/.git
#     of its own does NOT promote to user scope — it resolves to project
#     scope instead, same as any other unmatched boundary, so a stray
#     directory under $HOME can't be silently redirected into the shared
#     global ~/.claude or ~/.copilot agent directories.
#   - a .git file or directory marks the project-scope boundary (a worktree's
#     .git is a file, not a directory) — stop.
#   - filesystem root reached with neither found — project scope, same as
#     any other unmatched boundary.
find_package_root() {
  local root="$1" current="$1"
  while true; do
    if [[ -f "$current/apm.yml" ]] && is_apm_package_manifest "$current/apm.yml"; then
      echo "plugin $current"
      return
    fi
    if [[ "$current" == "$HOME" ]]; then
      if [[ "$current" == "$root" ]]; then
        echo "user $current"
        return
      fi
      echo "project $current"
      return
    fi
    if [[ -e "$current/.git" ]]; then
      echo "project $current"
      return
    fi
    local parent
    parent="$(dirname "$current")"
    if [[ "$parent" == "$current" ]]; then
      echo "project $current"
      return
    fi
    current="$parent"
  done
}

# `read` consumes a single line, so kind and path are emitted on one
# space-separated line rather than two `echo`s — kind first (never contains
# spaces), path last (absorbs any spaces in the path safely).
WALK_RESULT="$(find_package_root "$ROOT")"
read -r WALK_KIND WALK_ROOT <<< "$WALK_RESULT"

PACKAGE_ROOT=""
case "$WALK_KIND" in
  plugin)
    SCOPE="plugin"
    PACKAGE_ROOT="$WALK_ROOT"
    ;;
  user)
    SCOPE="user"
    ;;
  project)
    SCOPE="project"
    ;;
esac

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

created_any=false

if [[ "$SCOPE" == "plugin" ]]; then
  APM_FILE="$APM_DIR/$AGENT_NAME.agent.md"

  mkdir -p "$APM_DIR"

  if [[ -f "$APM_FILE" ]]; then
    echo "Skipping '$APM_FILE' — already exists." >&2
  else
    sed "s/AGENT_NAME/$AGENT_NAME/g" "$TEMPLATES_DIR/apm-agent.md" > "$APM_FILE"
    echo "Created: $APM_FILE" >&2
    created_any=true
  fi
else
  CC_FILE="$CC_DIR/$AGENT_NAME.md"
  CP_FILE="$CP_DIR/$AGENT_NAME.agent.md"

  mkdir -p "$CC_DIR"
  mkdir -p "$CP_DIR"

  # Copy Claude Code template (no-op if exists)
  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.template" > "$CP_FILE"
    echo "Created: $CP_FILE" >&2
    created_any=true
  fi
fi

# Create sources.md at plugin/APM package root (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 package.
     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:** .apm/agents/<name>.agent.md
- **Status:** `extracted` -->
SOURCES
    echo "Created: $SOURCES_FILE" >&2
    created_any=true
  fi
fi

# Next-steps guidance names no frontmatter fields, by rule (see references/scripts.md).
# A roster restated in terminal output goes stale one step further out than the list
# itself: the old "(name, description, model, body only)" hint outlived ADR-0016's
# 2026-08-14 amendment, which added disallowedTools to the permitted set. Point at the
# scaffolded file's own comments for what to fill, and at agent-audit's validate.sh —
# which reads the allowlist from field-inventory.md as data — for what is permitted.
AUDIT_SCRIPTS="$(cd "$SKILL_ROOT/../agent-audit/scripts" 2>/dev/null && pwd || true)"
if [[ -n "$AUDIT_SCRIPTS" && -f "$AUDIT_SCRIPTS/validate.sh" ]]; then
  VALIDATE_HINT="$AUDIT_SCRIPTS/validate.sh"
else
  VALIDATE_HINT="agent-audit's scripts/validate.sh"
fi

if [[ "$created_any" == false ]]; then
  echo "All files already exist — nothing to do." >&2
else
  echo "" >&2
  echo "Scope: $SCOPE" >&2
  echo "" >&2
  echo "Next steps:" >&2
  if [[ "$SCOPE" == "plugin" ]]; then
    echo "  1. Fill in $APM_FILE — replace every FILL IN: placeholder. Optional fields are" >&2
    echo "     scaffolded there as commented blocks; uncomment the ones that apply." >&2
    echo "  2. Populate $SOURCES_DIR/sources.md with research sources, or delete it" >&2
    echo "  3. Validate: $VALIDATE_HINT $APM_FILE" >&2
    echo "     It checks the frontmatter against the apm-agent-allowlist section of" >&2
    echo "     agent-audit's references/field-inventory.md, the authoritative field list." >&2
  else
    echo "  1. Fill in $CC_FILE — replace every FILL IN: placeholder. Optional fields are" >&2
    echo "     scaffolded there as commented blocks; uncomment the ones that apply." >&2
    echo "  2. Fill in $CP_FILE — same, and heed its closing comment: the Claude Code-only" >&2
    echo "     fields it names must not cross over from the file above." >&2
    echo "  3. Validate: run $VALIDATE_HINT on each file" >&2
  fi
fi