package ast

import (
	"bytes"
	"monna/token"
	"strings"
)

type Node interface {
	TokenLiteral() string
	String() string
}

type Statement interface {
	Node
	statement_node()
}

type Expression interface {
	Node
	expression_node()
}

func (l_program *Program) String() string {
	var out bytes.Buffer
	for _, s := range l_program.Statements {
		out.WriteString(s.String())
	}
	return out.String()
}

type Program struct {
	Statements []Statement
}

// Let Statements
type LetStatement struct {
	Token token.Token // token.LET token
	Name  *Identifier
	Value Expression
}

func (ls *LetStatement) statement_node() {}

func (ls *LetStatement) TokenLiteral() string {
	return ls.Token.Literal
}

func (ls *LetStatement) String() string {
	var out bytes.Buffer
	out.WriteString(ls.TokenLiteral() + " ")
	out.WriteString(ls.Name.String())
	out.WriteString(" = ")

	if ls.Value != nil {
		out.WriteString(ls.Value.String())
	}
	out.WriteString(";")
	return out.String()
}

// Identifier
type Identifier struct {
	Token token.Token // the token.IDENT token
	Value string
}

func (i *Identifier) expression_node() {}

func (i *Identifier) TokenLiteral() string {
	return i.Token.Literal
}

func (i *Identifier) String() string {
	return i.Value
}

// Program
func (p *Program) TokenLiteral() string {
	if len(p.Statements) > 0 {
		return p.Statements[0].TokenLiteral()
	} else {
		return ""
	}
}

// Return Statements
type ReturnStatement struct {
	Token       token.Token // token.RETURN token
	ReturnValue Expression
}

func (rs *ReturnStatement) statement_node() {}

func (rs *ReturnStatement) TokenLiteral() string {
	return rs.Token.Literal
}

func (rs *ReturnStatement) String() string {
	var out bytes.Buffer
	out.WriteString(rs.TokenLiteral() + " ")
	if rs.ReturnValue != nil {
		out.WriteString(rs.ReturnValue.String())
	}
	out.WriteString(";")
	return out.String()
}

// Expression Statement
type ExpressionStatement struct {
	Token      token.Token // the first token in the expression
	Expression Expression
}

func (es *ExpressionStatement) statement_node() {}

func (es *ExpressionStatement) TokenLiteral() string {
	return es.Token.Literal
}

func (es *ExpressionStatement) String() string {
	if es.Expression != nil {
		return es.Expression.String()
	}
	return ""
}

// IntegerLiteral
type IntegerLiteral struct {
	Token token.Token
	Value int64
}

func (il *IntegerLiteral) expression_node() {}

func (il *IntegerLiteral) TokenLiteral() string {
	return il.Token.Literal
}

func (il *IntegerLiteral) String() string {
	return il.Token.Literal
}

// PrefixExpression
type PrefixExpression struct {
	Token    token.Token // prefix token i.e. !
	Operator string
	Right    Expression
}

func (pe *PrefixExpression) expression_node() {}
func (pe *PrefixExpression) TokenLiteral() string {
	return pe.Token.Literal
}

func (pe *PrefixExpression) String() string {
	var out bytes.Buffer
	out.WriteString("(")
	out.WriteString(pe.Operator)
	out.WriteString(pe.Right.String())
	out.WriteString(")")

	return out.String()
}

// Infix Expression
type InfixExpression struct {
	Token    token.Token // operator tokens i.e. +, -, *, /
	Left     Expression
	Operator string
	Right    Expression
}

func (ie *InfixExpression) expression_node()     {}
func (ie *InfixExpression) TokenLiteral() string { return ie.Token.Literal }
func (ie *InfixExpression) String() string {
	var out bytes.Buffer
	out.WriteString("(")
	out.WriteString(ie.Left.String())
	out.WriteString(" " + ie.Operator + " ")
	out.WriteString(ie.Right.String())
	out.WriteString(")")

	return out.String()
}

// Booleans
type Boolean struct {
	Token token.Token
	Value bool
}

func (b *Boolean) expression_node()     {}
func (b *Boolean) TokenLiteral() string { return b.Token.Literal }
func (b *Boolean) String() string       { return b.Token.Literal }

// If Expression
type IfExpression struct {
	Token       token.Token // the 'if' token
	Condition   Expression
	Consequence *BlockStatement
	Alternative *BlockStatement
}

func (ie *IfExpression) expression_node()     {}
func (ie *IfExpression) TokenLiteral() string { return ie.Token.Literal }
func (ie *IfExpression) String() string {
	var out bytes.Buffer
	out.WriteString("if")
	out.WriteString(ie.Condition.String())
	out.WriteString(" ")
	out.WriteString(ie.Consequence.String())

	if ie.Alternative != nil {
		out.WriteString("else")
		out.WriteString(ie.Alternative.String())
	}
	return out.String()
}

// Block Statements
type BlockStatement struct {
	Token      token.Token // the { token
	Statements []Statement
}

func (bs *BlockStatement) statement_node() {}

func (bs *BlockStatement) TokenLiteral() string {
	return bs.Token.Literal
}
func (bs *BlockStatement) String() string {
	var out bytes.Buffer
	for _, s := range bs.Statements {
		out.WriteString(s.String())
	}
	return out.String()
}

// Function literals
type FunctionLiteral struct {
	Token      token.Token // the 'fn' token
	Parameters []*Identifier
	Body       *BlockStatement
}

func (fl *FunctionLiteral) expression_node()     {}
func (fl *FunctionLiteral) TokenLiteral() string { return fl.Token.Literal }
func (fl *FunctionLiteral) String() string {
	var out bytes.Buffer

	params := []string{}
	for _, p := range fl.Parameters {
		params = append(params, p.String())
	}
	out.WriteString(fl.TokenLiteral())
	out.WriteString("(")
	out.WriteString(strings.Join(params, ", "))
	out.WriteString(") ")
	out.WriteString(fl.Body.String())

	return out.String()
}

// Call Expression
type CallExpression struct {
	Token     token.Token // The '(' token
	Function  Expression  // Identifier or FunctionLiteral
	Arguments []Expression
}

func (ce *CallExpression) expression_node()     {}
func (ce *CallExpression) TokenLiteral() string { return ce.Token.Literal }
func (ce *CallExpression) String() string {
	var out bytes.Buffer

	args := []string{}
	for _, a := range ce.Arguments {
		args = append(args, a.String())
	}

	out.WriteString(ce.Function.String())
	out.WriteString("(")
	out.WriteString(strings.Join(args, ", "))
	out.WriteString(")")

	return out.String()
}

// String
type StringLiteral struct {
	Token token.Token
	Value string
}

func (sl *StringLiteral) expression_node()     {}
func (sl *StringLiteral) TokenLiteral() string { return sl.Token.Literal }
func (sl *StringLiteral) String() string       { return sl.Token.Literal }