package expression

import (
	"math"

	"git.akyoto.dev/cli/q/src/token"
)

// Operator represents an operator for mathematical expressions.
type Operator struct {
	Symbol     string
	Precedence int8
	Operands   int8
}

// Operators defines the operators used in the language.
// The number corresponds to the operator priority and can not be zero.
var Operators = [64]Operator{
	token.Period: {".", 13, 2},
	token.Call:   {"λ", 12, 1},
	token.Array:  {"@", 12, 2},
	token.Negate: {"-", 11, 1},
	token.Not:    {"!", 11, 1},
	token.Mul:    {"*", 10, 2},
	token.Div:    {"/", 10, 2},
	token.Mod:    {"%", 10, 2},
	token.Add:    {"+", 9, 2},
	token.Sub:    {"-", 9, 2},
	token.Shr:    {">>", 8, 2},
	token.Shl:    {"<<", 8, 2},
	token.And:    {"&", 7, 2},
	token.Xor:    {"^", 6, 2},
	token.Or:     {"|", 5, 2},

	token.Greater:      {">", 4, 2},
	token.Less:         {"<", 4, 2},
	token.GreaterEqual: {">=", 4, 2},
	token.LessEqual:    {"<=", 4, 2},
	token.Equal:        {"==", 3, 2},
	token.NotEqual:     {"!=", 3, 2},
	token.LogicalAnd:   {"&&", 2, 2},
	token.LogicalOr:    {"||", 1, 2},

	token.Separator: {",", 0, 2},

	token.Assign:    {"=", math.MinInt8, 2},
	token.Define:    {":=", math.MinInt8, 2},
	token.AddAssign: {"+=", math.MinInt8, 2},
	token.SubAssign: {"-=", math.MinInt8, 2},
	token.MulAssign: {"*=", math.MinInt8, 2},
	token.DivAssign: {"/=", math.MinInt8, 2},
	token.ModAssign: {"%=", math.MinInt8, 2},
	token.ShrAssign: {">>=", math.MinInt8, 2},
	token.ShlAssign: {"<<=", math.MinInt8, 2},
}

func isComplete(expr *Expression) bool {
	if expr == nil {
		return false
	}

	if expr.Token.Kind == token.Identifier || expr.Token.Kind == token.Number || expr.Token.Kind == token.String {
		return true
	}

	if expr.Token.Kind == token.Call {
		return true
	}

	if expr.Token.IsOperator() && len(expr.Children) == numOperands(expr.Token.Kind) {
		return true
	}

	return false
}

func numOperands(symbol token.Kind) int {
	return int(Operators[symbol].Operands)
}

func precedence(symbol token.Kind) int8 {
	return Operators[symbol].Precedence
}