package tools

import (
	"context"
	"os"
	"strconv"
	"strings"
	"testing"

	"charm.land/fantasy"
)

type (
	sessionIDContextKey string
	messageIDContextKey string
	supportsImagesKey   string
	modelNameKey        string
)

const (
	// SessionIDContextKey is the key for the session ID in the context.
	SessionIDContextKey sessionIDContextKey = "session_id"
	// MessageIDContextKey is the key for the message ID in the context.
	MessageIDContextKey messageIDContextKey = "message_id"
	// SupportsImagesContextKey is the key for the model's image support capability.
	SupportsImagesContextKey supportsImagesKey = "supports_images"
	// ModelNameContextKey is the key for the model name in the context.
	ModelNameContextKey modelNameKey = "model_name"
)

// getContextValue is a generic helper that retrieves a typed value from context.
// If the value is not found or has the wrong type, it returns the default value.
func getContextValue[T any](ctx context.Context, key any, defaultValue T) T {
	value := ctx.Value(key)
	if value == nil {
		return defaultValue
	}
	if typedValue, ok := value.(T); ok {
		return typedValue
	}
	return defaultValue
}

// GetSessionFromContext retrieves the session ID from the context.
func GetSessionFromContext(ctx context.Context) string {
	return getContextValue(ctx, SessionIDContextKey, "")
}

// GetMessageFromContext retrieves the message ID from the context.
func GetMessageFromContext(ctx context.Context) string {
	return getContextValue(ctx, MessageIDContextKey, "")
}

// GetSupportsImagesFromContext retrieves whether the model supports images from the context.
func GetSupportsImagesFromContext(ctx context.Context) bool {
	return getContextValue(ctx, SupportsImagesContextKey, false)
}

// GetModelNameFromContext retrieves the model name from the context.
func GetModelNameFromContext(ctx context.Context) string {
	return getContextValue(ctx, ModelNameContextKey, "")
}

// NewPermissionDeniedResponse returns a tool response indicating the user
// denied permission, with StopTurn set so the agent loop does not retry.
func NewPermissionDeniedResponse() fantasy.ToolResponse {
	resp := fantasy.NewTextErrorResponse("User denied permission")
	resp.StopTurn = true
	return resp
}

// FirstLineDescription returns just the first non-empty line from the embedded
// markdown description. The full description can be used by setting
// CRUSH_SHORT_TOOL_DESCRIPTIONS=0.
func FirstLineDescription(content []byte) string {
	if !testing.Testing() {
		if v, err := strconv.ParseBool(os.Getenv("CRUSH_SHORT_TOOL_DESCRIPTIONS")); err == nil && !v {
			return strings.TrimSpace(string(content))
		}
	}
	for line := range strings.SplitSeq(string(content), "\n") {
		line = strings.TrimSpace(line)
		if line != "" {
			return line
		}
	}
	return ""
}