package main

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

const stateFileName = ".imapdown_state.json"

// State tracks the highest UID downloaded per folder
type State map[string]uint32

// LoadState reads the state file from the base directory
// Returns empty state if file doesn't exist or can't be read
func LoadState(baseDir string, fullMode bool) (State, error) {
	if fullMode {
		return make(State), nil
	}

	statePath := filepath.Join(baseDir, stateFileName)

	data, err := os.ReadFile(statePath)
	if err != nil {
		if os.IsNotExist(err) {
			return make(State), nil
		}
		return make(State), err
	}

	var state State
	if err := json.Unmarshal(data, &state); err != nil {
		// Return empty state on parse error
		return make(State), nil
	}

	return state, nil
}

// SaveState writes the state file to the base directory with indentation
func SaveState(baseDir string, state State) error {
	statePath := filepath.Join(baseDir, stateFileName)

	data, err := json.MarshalIndent(state, "", "  ")
	if err != nil {
		return err
	}

	return os.WriteFile(statePath, data, 0644)
}

// UpdateFolder updates the highest UID for a folder
func (s State) UpdateFolder(folder string, uid uint32) {
	if current, exists := s[folder]; !exists || uid > current {
		s[folder] = uid
	}
}

// GetLastUID returns the last UID for a folder, or 0 if not found
func (s State) GetLastUID(folder string) uint32 {
	if uid, exists := s[folder]; exists {
		return uid
	}
	return 0
}