package tui

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

const promptHistoryMax = 100

// DefaultPromptHistoryPath returns the path for persistent prompt history.
func DefaultPromptHistoryPath() string {
    home, err := os.UserHomeDir()
    if err != nil {
        return "prompt_history.json"
    }
    return filepath.Join(home, ".config", "ai-agent", "prompt_history.json")
}

// LoadPromptHistory reads saved prompt history from path. Returns nil on error or missing file.
func LoadPromptHistory(path string) ([]string, error) {
    data, err := os.ReadFile(path)
    if err != nil {
        if os.IsNotExist(err) {
            return nil, nil
        }
        return nil, err
    }
    var list []string
    if err := json.Unmarshal(data, &list); err != nil {
        return nil, err
    }
    if len(list) > promptHistoryMax {
        list = list[len(list)-promptHistoryMax:]
    }
    return list, nil
}

// SavePromptHistory writes prompt history to path, creating the directory if needed.
func SavePromptHistory(path string, items []string) error {
    dir := filepath.Dir(path)
    if err := os.MkdirAll(dir, 0o755); err != nil {
        return err
    }
    data, err := json.MarshalIndent(items, "", "  ")
    if err != nil {
        return err
    }
    return os.WriteFile(path, data, 0o644)
}