// Copyright © 2016 Abcum Ltd
//
// 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 sql

func (p *parser) parseCond() (mul []Expr, err error) {

	var tok Token
	var lit string

	// Remove the WHERE keyword
	if _, _, exi := p.mightBe(WHERE); !exi {
		return nil, nil
	}

	for {

		one := &BinaryExpression{}

		tok, lit, err = p.shouldBe(ID, IDENT, THING, NULL, VOID, MISSING, EMPTY, NOW, DATE, TIME, TRUE, FALSE, STRING, REGION, NUMBER, DOUBLE, REGEX, JSON, ARRAY, PARAM)
		if err != nil {
			return nil, &ParseError{Found: lit, Expected: []string{"field name"}}
		}

		one.LHS, err = p.declare(tok, lit)
		if err != nil {
			return nil, err
		}

		tok, lit, err = p.shouldBe(IS, IN, EQ, NEQ, EEQ, NEE, ANY, LT, LTE, GT, GTE, SIN, SNI, INS, NIS, CONTAINS, CONTAINSALL, CONTAINSNONE, CONTAINSSOME, ALLCONTAINEDIN, NONECONTAINEDIN, SOMECONTAINEDIN)
		if err != nil {
			return nil, err
		}
		one.Op = tok

		if tok == IN {
			one.Op = INS
		}

		if tok == IS {
			one.Op = EQ
			if _, _, exi := p.mightBe(NOT); exi {
				one.Op = NEQ
			}
			if _, _, exi := p.mightBe(IN); exi {
				switch one.Op {
				case EQ:
					one.Op = INS
				case NEQ:
					one.Op = NIS
				}
			}
		}

		if tok == CONTAINS {
			one.Op = SIN
			if _, _, exi := p.mightBe(NOT); exi {
				one.Op = SNI
			}
		}

		tok, lit, err = p.shouldBe(ID, IDENT, THING, NULL, VOID, MISSING, EMPTY, NOW, DATE, TIME, TRUE, FALSE, STRING, REGION, NUMBER, DOUBLE, REGEX, JSON, ARRAY, PARAM)
		if err != nil {
			return nil, &ParseError{Found: lit, Expected: []string{"field value"}}
		}

		one.RHS, err = p.declare(tok, lit)
		if err != nil {
			return nil, err
		}

		mul = append(mul, one)

		if _, _, exi := p.mightBe(AND, OR); !exi {
			break
		}

	}

	return mul, nil

}