package config

import (
	"fmt"
	"os"
	"strconv"
	"strings"
)

// Config holds CLI configuration.
type Config struct {
	Mode               string // "new" or "resume"
	Task               string
	SessionID          string
	WorkDir            string
	OutputPath         string
	Model              string
	ReasoningEffort    string
	ExplicitStdin      bool
	Timeout            int
	Backend            string
	Agent              string
	PromptFile         string
	PromptFileExplicit bool
	SkipPermissions    bool
	Yolo               bool
	MaxParallelWorkers int
	AllowedTools       []string
	DisallowedTools    []string
	Skills             []string
	Worktree           bool // Execute in a new git worktree
}

// EnvFlagEnabled returns true when the environment variable exists and is not
// explicitly set to a falsey value ("0/false/no/off").
func EnvFlagEnabled(key string) bool {
	val, ok := os.LookupEnv(key)
	if !ok {
		return false
	}
	val = strings.TrimSpace(strings.ToLower(val))
	switch val {
	case "", "0", "false", "no", "off":
		return false
	default:
		return true
	}
}

func ParseBoolFlag(val string, defaultValue bool) bool {
	val = strings.TrimSpace(strings.ToLower(val))
	switch val {
	case "1", "true", "yes", "on":
		return true
	case "0", "false", "no", "off":
		return false
	default:
		return defaultValue
	}
}

// EnvFlagDefaultTrue returns true unless the env var is explicitly set to
// false/0/no/off.
func EnvFlagDefaultTrue(key string) bool {
	val, ok := os.LookupEnv(key)
	if !ok {
		return true
	}
	return ParseBoolFlag(val, true)
}

func ValidateAgentName(name string) error {
	if strings.TrimSpace(name) == "" {
		return fmt.Errorf("agent name is empty")
	}
	for _, r := range name {
		switch {
		case r >= 'a' && r <= 'z':
		case r >= 'A' && r <= 'Z':
		case r >= '0' && r <= '9':
		case r == '-', r == '_':
		default:
			return fmt.Errorf("agent name %q contains invalid character %q", name, r)
		}
	}
	return nil
}

const maxParallelWorkersLimit = 100

// ResolveMaxParallelWorkers reads CODEAGENT_MAX_PARALLEL_WORKERS. It returns 0
// for "unlimited".
func ResolveMaxParallelWorkers() int {
	raw := strings.TrimSpace(os.Getenv("CODEAGENT_MAX_PARALLEL_WORKERS"))
	if raw == "" {
		return 0
	}

	value, err := strconv.Atoi(raw)
	if err != nil || value < 0 {
		return 0
	}
	if value > maxParallelWorkersLimit {
		return maxParallelWorkersLimit
	}
	return value
}