package resources

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

// Trust is how a project directory is treated in non-interactive runs.
type Trust string

const (
	TrustAsk    Trust = "ask"
	TrustAlways Trust = "always"
	TrustNever  Trust = "never"
)

// Settings is the global plus project configuration.
type Settings struct {
	Trust    Trust             `json:"trust,omitempty"`
	Model    string            `json:"model,omitempty"`
	Thinking string            `json:"thinking,omitempty"`
	Tools    []string          `json:"tools,omitempty"`
	Exclude  []string          `json:"exclude,omitempty"`
	Vars     map[string]string `json:"vars,omitempty"`
}

// LoadSettings reads global (optional) then project settings.
// Project keys override global keys. A missing file is an empty settings.
func LoadSettings(globalPath, projectPath string) (Settings, error) {
	global, err := readSettings(globalPath)
	if err != nil {
		return Settings{}, err
	}
	project, err := readSettings(projectPath)
	if err != nil {
		return Settings{}, err
	}
	return mergeSettings(global, project), nil
}

// ProjectTrusted reports whether project resources may be loaded.
// ask and never refuse in non-interactive mode. approve forces trust.
func ProjectTrusted(trust Trust, approve, noApprove bool) bool {
	if noApprove {
		return false
	}
	if approve {
		return true
	}
	return trust == TrustAlways
}

func readSettings(path string) (Settings, error) {
	if path == "" {
		return Settings{}, nil
	}
	raw, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return Settings{}, nil
		}
		return Settings{}, err
	}
	var s Settings
	if err := json.Unmarshal(raw, &s); err != nil {
		return Settings{}, err
	}
	return s, nil
}

func mergeSettings(base, over Settings) Settings {
	if over.Trust != "" {
		base.Trust = over.Trust
	}
	if over.Model != "" {
		base.Model = over.Model
	}
	if over.Thinking != "" {
		base.Thinking = over.Thinking
	}
	if over.Tools != nil {
		base.Tools = over.Tools
	}
	if over.Exclude != nil {
		base.Exclude = over.Exclude
	}
	if len(over.Vars) > 0 {
		if base.Vars == nil {
			base.Vars = map[string]string{}
		}
		for k, v := range over.Vars {
			base.Vars[k] = v
		}
	}
	return base
}

// DefaultPaths returns the global and project settings paths for a cwd.
func DefaultPaths(home, cwd string) (string, string) {
	return filepath.Join(home, ".agent-native", "settings.json"), filepath.Join(cwd, ".agent-native", "settings.json")
}