// Copyright (C) 2014 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package parser

import (
	"android.googlesource.com/platform/tools/gpu/api/ast"
	"android.googlesource.com/platform/tools/gpu/parse"
)

func identifier(p *parse.Parser, cst *parse.Branch) *ast.Identifier {
	if !p.AlphaNumeric() {
		return nil
	}
	n := &ast.Identifier{}
	p.ParseLeaf(cst, func(p *parse.Parser, l *parse.Leaf) {
		n.CST = l
		l.SetToken(p.Consume())
		n.Value = l.Token().String()
	})
	return n
}

func requireIdentifier(p *parse.Parser, cst *parse.Branch) *ast.Identifier {
	n := identifier(p, cst)
	if n == nil {
		p.Expected("Identifier")
	}
	return n
}

// name '!' ( type | '(' type [ ',' type ] ')' )
func generic(p *parse.Parser, cst *parse.Branch) *ast.Generic {
	i := identifier(p, cst)
	if i == nil {
		return nil
	}
	g := &ast.Generic{Name: i}
	p.ParseBranch(cst, func(p *parse.Parser, cst *parse.Branch) {
		g.CST = cst
		if operator(ast.OpGeneric, p, cst) {
			if operator(ast.OpListStart, p, cst) {
				for !operator(ast.OpListEnd, p, cst) {
					if len(g.Arguments) > 0 {
						requireOperator(ast.OpListSeparator, p, cst)
					}
					g.Arguments = append(g.Arguments, requireTypeRef(p, cst))
				}
			} else {
				g.Arguments = append(g.Arguments, requireTypeRef(p, cst))
			}
		}
	})
	return g
}

func requireGeneric(p *parse.Parser, cst *parse.Branch) *ast.Generic {
	n := generic(p, cst)
	if n == nil {
		p.Expected("generic identifier")
	}
	return n
}

func peekKeyword(k string, p *parse.Parser) bool {
	if !p.AlphaNumeric() {
		return false
	}
	if p.Token().String() != string(k) {
		p.Rollback()
		return false
	}
	p.Rollback()
	return true
}

func keyword(k string, p *parse.Parser, cst *parse.Branch) *parse.Leaf {
	if !p.AlphaNumeric() {
		return nil
	}
	if p.Token().String() != string(k) {
		p.Rollback()
		return nil
	}
	var result *parse.Leaf
	p.ParseLeaf(cst, func(p *parse.Parser, l *parse.Leaf) {
		result = l
	})
	return result
}

func requireKeyword(k string, p *parse.Parser, cst *parse.Branch) {
	if keyword(k, p, cst) == nil {
		p.Expected(string(k))
	}
}