// Package state manages the persistent xetup deployment state used to resume
// after a system reboot. The state file is written before each reboot and
// deleted once all deployment steps have completed.
package state

import (
	"encoding/json"
	"os"
	"path/filepath"
	"time"

	"git.xetup.x9.cz/x9/xetup/internal/config"
)

// StepResult records the outcome of a single deployment step.
// Results are accumulated across reboot rounds so the final summary
// can show every step regardless of which round it ran in.
type StepResult struct {
	StepID  string        `json:"stepID"`
	Num     string        `json:"num"`
	Name    string        `json:"name"`
	Status  string        `json:"status"`  // "OK", "ERROR", "SKIPPED"
	Elapsed time.Duration `json:"elapsed"`
}

// State holds everything xetup needs to resume after a reboot.
type State struct {
	Config       config.Config `json:"config"`
	ConfigPath   string        `json:"configPath"` // path to original config.json
	LogFile      string        `json:"logFile"`
	PendingSteps []string      `json:"pendingSteps"` // step IDs to run next, in canonical order
	Results      []StepResult  `json:"results"`      // accumulated across all rounds
}

// Load reads the state file. Returns a non-nil error when the file is absent.
func Load() (*State, error) {
	data, err := os.ReadFile(statePath())
	if err != nil {
		return nil, err
	}
	var s State
	if err := json.Unmarshal(data, &s); err != nil {
		return nil, err
	}
	return &s, nil
}

// Save writes the state file, creating parent directories as needed.
func Save(s *State) error {
	p := statePath()
	if err := os.MkdirAll(filepath.Dir(p), 0755); err != nil {
		return err
	}
	data, err := json.MarshalIndent(s, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(p, data, 0644)
}

// Delete removes the state file. Silently ignores not-found.
func Delete() error {
	err := os.Remove(statePath())
	if os.IsNotExist(err) {
		return nil
	}
	return err
}

// Exists reports whether a state file is present on disk.
func Exists() bool {
	_, err := os.Stat(statePath())
	return err == nil
}