// VulcanizeDB
// Copyright © 2019 Vulcanize

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package mocks

import (
	"github.com/ethereum/go-ethereum/accounts/abi"

	"github.com/vulcanize/vulcanizedb/pkg/contract_watcher/shared/types"
	"github.com/vulcanize/vulcanizedb/pkg/geth"
)

// Mock parser
// Is given ABI string instead of address
// Performs all other functions of the real parser
type parser struct {
	abi       string
	parsedAbi abi.ABI
}

func NewParser(abi string) *parser {

	return &parser{
		abi: abi,
	}
}

func (p *parser) Abi() string {
	return p.abi
}

func (p *parser) ParsedAbi() abi.ABI {
	return p.parsedAbi
}

// Retrieves and parses the abi string
// for the given contract address
func (p *parser) Parse() error {
	var err error
	p.parsedAbi, err = geth.ParseAbi(p.abi)

	return err
}

// Returns only specified methods, if they meet the criteria
// Returns as array with methods in same order they were specified
// Nil wanted array => no events are returned
func (p *parser) GetSelectMethods(wanted []string) []types.Method {
	wLen := len(wanted)
	if wLen == 0 {
		return nil
	}
	methods := make([]types.Method, wLen)
	for _, m := range p.parsedAbi.Methods {
		for i, name := range wanted {
			if name == m.Name && okTypes(m, wanted) {
				methods[i] = types.NewMethod(m)
			}
		}
	}

	return methods
}

// Returns wanted methods
// Empty wanted array => all methods are returned
// Nil wanted array => no methods are returned
func (p *parser) GetMethods(wanted []string) []types.Method {
	if wanted == nil {
		return nil
	}
	methods := make([]types.Method, 0)
	length := len(wanted)
	for _, m := range p.parsedAbi.Methods {
		if length == 0 || stringInSlice(wanted, m.Name) {
			methods = append(methods, types.NewMethod(m))
		}
	}

	return methods
}

// Returns wanted events as map of types.Events
// If no events are specified, all events are returned
func (p *parser) GetEvents(wanted []string) map[string]types.Event {
	events := map[string]types.Event{}

	for _, e := range p.parsedAbi.Events {
		if len(wanted) == 0 || stringInSlice(wanted, e.Name) {
			event := types.NewEvent(e)
			events[e.Name] = event
		}
	}

	return events
}

func stringInSlice(list []string, s string) bool {
	for _, b := range list {
		if b == s {
			return true
		}
	}

	return false
}

func okTypes(m abi.Method, wanted []string) bool {
	// Only return method if it has less than 3 arguments, a single output value, and it is a method we want or we want all methods (empty 'wanted' slice)
	if len(m.Inputs) < 3 && len(m.Outputs) == 1 && (len(wanted) == 0 || stringInSlice(wanted, m.Name)) {
		// Only return methods if inputs are all of accepted types and output is of the accepted types
		if !okReturnType(m.Outputs[0]) {
			return false
		}
		for _, input := range m.Inputs {
			switch input.Type.T {
			case abi.AddressTy, abi.HashTy, abi.BytesTy, abi.FixedBytesTy:
			default:
				return false
			}
		}

		return true
	}

	return false
}

func okReturnType(arg abi.Argument) bool {
	wantedTypes := []byte{
		abi.UintTy,
		abi.IntTy,
		abi.BoolTy,
		abi.StringTy,
		abi.AddressTy,
		abi.HashTy,
		abi.BytesTy,
		abi.FixedBytesTy,
		abi.FixedPointTy,
	}

	for _, ty := range wantedTypes {
		if arg.Type.T == ty {
			return true
		}
	}

	return false
}