package settings

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"time"
)

// Stable IDs for seeded built-in actions.
const (
	BuiltinActionUptimeID    = "00000000-0000-4000-8000-000000000001"
	BuiltinActionDiskUsageID = "00000000-0000-4000-8000-000000000002"
	BuiltinActionSysInfoID   = "00000000-0000-4000-8000-000000000003"
)

// DefaultBuiltinActions returns the read-only seed actions.
func DefaultBuiltinActions() []Action {
	now := time.Now().UTC()
	return []Action{
		{
			ID:          BuiltinActionUptimeID,
			Name:        "Uptime",
			Description: "Show how long the target system has been running.",
			Kind:        ActionKindShell,
			Body:        "uptime",
			Env:         []ActionEnvVar{},
			Builtin:     true,
			CreatedAt:   now,
			UpdatedAt:   now,
		},
		{
			ID:          BuiltinActionDiskUsageID,
			Name:        "Disk usage",
			Description: "Show filesystem disk space usage on the target.",
			Kind:        ActionKindShell,
			Body:        "df -h",
			Env:         []ActionEnvVar{},
			Builtin:     true,
			CreatedAt:   now,
			UpdatedAt:   now,
		},
		{
			ID:          BuiltinActionSysInfoID,
			Name:        "System info",
			Description: "Print kernel and OS release details from the target.",
			Kind:        ActionKindScript,
			Body: `uname -a
if [ -f /etc/os-release ]; then
  . /etc/os-release
  echo "OS: ${NAME:-unknown} ${VERSION:-}"
fi`,
			Env:       []ActionEnvVar{},
			Builtin:   true,
			CreatedAt: now,
			UpdatedAt: now,
		},
	}
}

// LoadActions reads and parses actions.json from dir.
func LoadActions(dir string) (ActionStore, error) {
	path := filepath.Join(dir, ActionsFileName)
	payload, err := os.ReadFile(path)
	if err != nil {
		return ActionStore{}, err
	}

	var store ActionStore
	if err := json.Unmarshal(payload, &store); err != nil {
		return ActionStore{}, fmt.Errorf("parse actions: %w", err)
	}
	if store.Actions == nil {
		store.Actions = []Action{}
	}
	for index := range store.Actions {
		if store.Actions[index].Env == nil {
			store.Actions[index].Env = []ActionEnvVar{}
		}
	}
	return store, nil
}

// LoadActionsOrSeed returns seeded builtins (and persists them) when actions.json is missing.
func LoadActionsOrSeed(dir string) (ActionStore, error) {
	store, err := LoadActions(dir)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			seeded := ActionStore{Actions: DefaultBuiltinActions()}
			if saveErr := SaveActions(dir, seeded); saveErr != nil {
				return ActionStore{}, saveErr
			}
			return seeded, nil
		}
		return ActionStore{}, err
	}
	return store, nil
}

// SaveActions writes actions.json to dir with mode 0640.
func SaveActions(dir string, store ActionStore) error {
	if err := ensureConfigDir(dir); err != nil {
		return err
	}
	if store.Actions == nil {
		store.Actions = []Action{}
	}
	for index := range store.Actions {
		if store.Actions[index].Env == nil {
			store.Actions[index].Env = []ActionEnvVar{}
		}
	}

	payload, err := json.MarshalIndent(store, "", "  ")
	if err != nil {
		return fmt.Errorf("encode actions: %w", err)
	}
	payload = append(payload, '\n')

	path := filepath.Join(dir, ActionsFileName)
	if err := os.WriteFile(path, payload, 0o640); err != nil {
		return fmt.Errorf("write actions: %w", err)
	}
	return nil
}