package calculator

import (
	"context"
	"fmt"
	"strconv"
	"strings"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/plugin"
)

type Plugin struct{}
func New() *Plugin { return &Plugin{} }
func (p *Plugin) Name() string { return "calculator" }
func (p *Plugin) Version() string { return "1.0.0" }
func (p *Plugin) Description() string { return "数学表达式求值" }
func (p *Plugin) Init(_ context.Context, _ plugin.PluginConfig) error { return nil }
func (p *Plugin) Close() error { return nil }
func (p *Plugin) Enabled() bool { return true }

func (p *Plugin) Tools() []plugin.ToolDefinition {
	return []plugin.ToolDefinition{{
		Name:        "calculator",
		Description: "Evaluate a math expression (supports +, -, *, /, parentheses)",
		Parameters:  map[string]any{"expression": map[string]string{"type": "string", "description": "Math expression"}},
	}}
}

func (p *Plugin) Execute(_ context.Context, _ string, params map[string]any) (string, error) {
	expr, _ := params["expression"].(string)
	if expr == "" {
		return "", fmt.Errorf("missing expression")
	}
	result, err := evalSimple(expr)
	if err != nil {
		return "", err
	}
	return fmt.Sprintf("%v", result), nil
}

func evalSimple(expr string) (float64, error) {
	expr = strings.ReplaceAll(expr, " ", "")
	// Simple operator evaluation: split by + and -, then by * and /
	parts := strings.FieldsFunc(expr, func(r rune) bool { return r == '+' || r == '-' })
	if len(parts) == 1 {
		return evalMulDiv(expr)
	}
	var result float64
	idx := 0
	for i, p := range parts {
		val, err := evalMulDiv(p)
		if err != nil {
			return 0, err
		}
		if i == 0 {
			result = val
		} else {
			op := expr[idx-1]
			if op == '+' {
				result += val
			} else {
				result -= val
			}
		}
		idx += len(p) + 1
	}
	return result, nil
}

func evalMulDiv(expr string) (float64, error) {
	parts := strings.FieldsFunc(expr, func(r rune) bool { return r == '*' || r == '/' })
	if len(parts) == 1 {
		return strconv.ParseFloat(expr, 64)
	}
	var result float64
	idx := 0
	for i, p := range parts {
		val, err := strconv.ParseFloat(p, 64)
		if err != nil { return 0, err }
		if i == 0 {
			result = val
		} else {
			op := expr[idx-1]
			if op == '*' { result *= val } else { result /= val }
		}
		idx += len(p) + 1
	}
	return result, nil
}