// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package search

import (
	"strings"
)

// ParseInputType parses the search query input and returns the InputType. The
// InputType determines which symbol search query will be run.
func ParseInputType(q string) InputType {
	q = strings.TrimSpace(q)
	if strings.ContainsAny(q, " \t\n") {
		return InputTypeMultiWord
	}
	parts := strings.Split(q, ".")
	switch strings.Count(q, ".") {
	case 0:
		return InputTypeNoDot
	case 1:
		return InputTypeOneDot
	case 2:
		if strings.Contains(parts[1], "/") {
			// Example: if q = "github.com/foo/bar", parts[1] will be
			// "com/foo/bar.DB".
			// <package-path>.<symbol> is currently not a supported search when
			// package path is not a standard library path.
			return InputTypeNoMatch
		}
		return InputTypeTwoDots
	default:
		return InputTypeNoMatch
	}
}

// InputType is the type determined for the search query input.
type InputType int

const (
	// InputTypeNoMatch indicates that there is no situation where we will get
	// results for this search input.
	InputTypeNoMatch InputType = iota

	// InputTypeNoDot indicates that the query type is <symbol>.
	//
	// If the search input contains only 1 word with no dots, it must be the
	// symbol name.
	InputTypeNoDot

	// InputTypeOneDot indicates that the query type is <package>.<symbol> or
	// <type>.<fieldOrMethod>.
	//
	// If the search input contains only 1 word split by 1 dot, the search must
	// either be for <package>.<symbol> or <type>.<methodOrFieldName>.
	InputTypeOneDot

	// InputTypeTwoDots indicates that the query type is
	// <package>.<type>.<fieldOrMethod>.
	//
	// If the search input contains only 1 word split by 1 dot, the search must
	// be for <package>.<type>.<methodOrFieldName>.
	// TODO(golang/go#44142): This could also be a search for
	// <package-path>.<symbol>, but that case is not currently handled.
	InputTypeTwoDots

	// InputTypeMultiWord indicates that the query has multiple words.
	InputTypeMultiWord
)

// SearchType is the type of search that will be performed, based on the input
// type.
type SearchType int

const (
	// SearchTypeSymbol is used for InputTypeNoDot (input is <symbol>) or
	// InputTypeOneDot (input is <type>.<fieldOrMethod>).
	SearchTypeSymbol SearchType = iota

	// SearchTypePackageDotSymbol is used for
	// InputTypeNoDot (input is <package>.<symbol>) or
	// InputTypeTwoDots (input is <package>.<type>.<fieldOrMethod>).
	SearchTypePackageDotSymbol

	// SearchTypeMultiWordOr is used for InputTypeMultiWord when the
	// search query cannot be used to generate a reasonable number of symbol
	// and path token combinations. In that case, an OR search is performed on
	// all of the words in the search input.
	SearchTypeMultiWordOr

	// SearchTypeMultiExact is used for InputTypeMultiWord when the search
	// query can be used to construct a reasonable number of symbol and path
	// token combinations. In that case, multiple queries are run in parallel
	// and the results are combined.
	SearchTypeMultiWordExact
)

// String returns the name of the search type as a string.
func (st SearchType) String() string {
	switch st {
	case SearchTypeSymbol:
		return "SearchTypeSymbol"
	case SearchTypePackageDotSymbol:
		return "SearchTypePackageDotSymbol"
	case SearchTypeMultiWordOr:
		return "SearchTypeMultiWordOr"
	case SearchTypeMultiWordExact:
		return "SearchTypeMultiWordExact"
	default:
		// This should never happen.
		return "?unknown?"
	}
}