package main

import (
	"fmt"
	"math"

	"github.com/expr-lang/expr"
	"github.com/gdamore/tcell/v2"
	"github.com/rivo/tview"
)

func main() {
	app := tview.NewApplication()

	env := map[string]any{
		"abs":   math.Abs,
		"acos":  math.Acos,
		"asin":  math.Asin,
		"atan":  math.Atan,
		"atan2": math.Atan2,
		"ceil":  math.Ceil,
		"cos":   math.Cos,
		"cosh":  math.Cosh,
		"exp":   math.Exp,
		"floor": math.Floor,
		"log":   math.Log,
		"log10": math.Log10,
		"max":   math.Max,
		"min":   math.Min,
		"mod":   math.Mod,
		"pow":   math.Pow,
		"round": math.Round,
		"sin":   math.Sin,
		"sinh":  math.Sinh,
		"sqrt":  math.Sqrt,
		"tan":   math.Tan,
		"tanh":  math.Tanh,
		"pi":    math.Pi,
		"e":     math.E,
	}

	title := tview.NewTextView()
	title.SetText("🧮 [::b]Math Expression Evaluator[-]")
	title.SetTextAlign(tview.AlignCenter)
	title.SetDynamicColors(true)
	title.SetBorder(true)
	title.SetBorderColor(tcell.ColorLightBlue)

	result := tview.NewTextView()
	result.SetDynamicColors(true)
	result.SetWrap(true)
	result.SetChangedFunc(func() { app.Draw() })
	result.SetBorder(true)
	result.SetTitle("Result")
	result.SetTitleAlign(tview.AlignLeft)

	help := tview.NewTextView()
	help.SetText("[yellow]Functions: sqrt, pow, abs, sin, cos, tan...\nConstants: pi, e")
	help.SetDynamicColors(true)
	help.SetWrap(true)
	help.SetBorder(true)
	help.SetTitle("Help")
	help.SetTitleAlign(tview.AlignLeft)

	input := tview.NewInputField()
	input.SetLabel("Expression: ")
	input.SetFieldWidth(60)
	input.SetDoneFunc(func(key tcell.Key) {
		if key == tcell.KeyEnter {
			exprStr := input.GetText()

			program, err := expr.Compile(exprStr, expr.Env(env))
			if err != nil {
				result.SetText(fmt.Sprintf("[red]Compile error: %v", err))
				return
			}
			output, err := expr.Run(program, env)
			if err != nil {
				result.SetText(fmt.Sprintf("[red]Runtime error: %v", err))
				return
			}
			result.SetText(fmt.Sprintf("[green]Result: %v", output))
		}
	})
	input.SetBorder(true)
	input.SetTitle("Input")
	input.SetTitleAlign(tview.AlignLeft)

	mainFlex := tview.NewFlex()
	mainFlex.SetDirection(tview.FlexRow)
	mainFlex.AddItem(title, 3, 1, false)
	mainFlex.AddItem(input, 5, 0, true)
	mainFlex.AddItem(result, 5, 0, false)
	mainFlex.AddItem(help, 3, 1, false)

	app.SetRoot(mainFlex, true)
	app.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
		if event.Key() == tcell.KeyEsc || event.Key() == tcell.KeyCtrlC {
			app.Stop()
			return nil
		}
		return event
	})

	if err := app.Run(); err != nil {
		panic(err)
	}
}