[fix] a more robust parser for views (Snowflake-Labs#185)

[fix] a more robust parser for viewsIn order to extract the select statement from views we need a more robust parser.

So far it can parse all query shapes generated by this project and many others, which are relevant since they can come in via imports.

## Test Plan
* [x] acceptance tests
* [x] tested on our internal snowflake infra repo

## References
*  https://docs.snowflake.com/en/sql-reference/sql/create-view.html

Makefile

@@ -55,7 +55,7 @@ coverage: ## run the go coverage tool, reading file coverage.out
 .PHONY: coverage
 
 test: fmt deps ## run the tests
-	go test -race -coverprofile=coverage.txt -covermode=atomic ./...
+	go test -race -coverprofile=coverage.txt -covermode=atomic $(TESTARGS) ./...
 .PHONY: test
 
 test-acceptance: fmt deps ## runs all tests, including the acceptance tests which create and destroys real resources
@@ -79,6 +79,10 @@ install-tf: build ## installs plugin where terraform can find it
 	cp ./$(BASE_BINARY_NAME) $(HOME)/.terraform.d/plugins/$(BASE_BINARY_NAME)
 .PHONY: install-tf
 
+uninstall-tf: build ## uninstalls plugin from where terraform can find it
+	rm $(HOME)/.terraform.d/plugins/$(BASE_BINARY_NAME) 2>/dev/null
+.PHONY: install-tf
+
 help: ## display help for this makefile
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
 .PHONY: help

pkg/resources/view.go

@@ -160,9 +160,13 @@ func ReadView(data *schema.ResourceData, meta interface{}) error {
 	}
 
 	// Want to only capture the Select part of the query because before that is the Create part of the view which we no longer care about
-	cleanString := space.ReplaceAllString(text.String, " ")
-	indexOfSelect := strings.Index(strings.ToUpper(cleanString), " AS SELECT")
-	substringOfQuery := cleanString[indexOfSelect+4:]
+
+	extractor := snowflake.NewViewSelectStatementExtractor(text.String)
+	substringOfQuery, err := extractor.Extract()
+	if err != nil {
+		return err
+	}
+
 	err = data.Set("statement", substringOfQuery)
 	if err != nil {
 		return err

pkg/snowflake/parser.go

@@ -0,0 +1,139 @@
+package snowflake
+
+import (
+	"fmt"
+	"strings"
+	"unicode"
+)
+
+// ViewSelectStatementExtractor is a simplistic parser that only exists to extract the select
+// statement from a create view statement
+//
+// The implementation is optimized for undertandable and predictable behavior. So far we only seek
+// to support queries of the sort that are generated by this project.
+//
+// Also there is little error handling and we assume queries are well-formed.
+type ViewSelectStatementExtractor struct {
+	input []rune
+	pos   int
+}
+
+func NewViewSelectStatementExtractor(input string) *ViewSelectStatementExtractor {
+	return &ViewSelectStatementExtractor{
+		input: []rune(input),
+	}
+}
+
+func (e *ViewSelectStatementExtractor) Extract() (string, error) {
+	fmt.Printf("[DEBUG] extracting view query %s\n", string(e.input))
+	e.consumeSpace()
+	e.consumeToken("create")
+	e.consumeSpace()
+	e.consumeToken("or replace")
+	e.consumeSpace()
+	e.consumeToken("secure")
+	e.consumeSpace()
+	e.consumeToken("recursive")
+	e.consumeSpace()
+	e.consumeToken("view")
+	e.consumeSpace()
+	e.consumeToken("if not exists")
+	e.consumeSpace()
+	e.consumeIdentifier()
+	// TODO column list
+	// TODO copy grants
+	e.consumeComment()
+	e.consumeSpace()
+	e.consumeComment()
+	e.consumeSpace()
+	e.consumeToken("as")
+	e.consumeSpace()
+
+	return string(e.input[e.pos:]), nil
+}
+
+// consumeToken will move e.pos forward iff the token is the next part of the input. Comparison is
+// case-insensitive. Will return true if consumed.
+func (e *ViewSelectStatementExtractor) consumeToken(t string) bool {
+	found := 0
+	for i, r := range t {
+		// it is annoying that we have to convert the runes back to strings to do a case-insensitive
+		// comparison. Hopefully I am just missing something in the docs.
+		if e.pos+i > len(e.input) || !strings.EqualFold(string(r), string(e.input[e.pos+i])) {
+			break
+		}
+		found += 1
+	}
+
+	if found == len(t) {
+		e.pos += len(t)
+		return true
+	}
+	return false
+}
+
+func (e *ViewSelectStatementExtractor) consumeSpace() {
+	found := 0
+	for {
+		if e.pos+found > len(e.input)-1 || !unicode.IsSpace(e.input[e.pos+found]) {
+			break
+		}
+		found += 1
+	}
+	e.pos += found
+}
+
+func (e *ViewSelectStatementExtractor) consumeIdentifier() {
+	e.consumeNonSpace()
+}
+
+func (e *ViewSelectStatementExtractor) consumeNonSpace() {
+	found := 0
+	for {
+		if e.pos+found > len(e.input)-1 || unicode.IsSpace(e.input[e.pos+found]) {
+			break
+		}
+		found += 1
+	}
+	e.pos += found
+}
+
+func (e *ViewSelectStatementExtractor) consumeComment() {
+	if c := e.consumeToken("comment"); !c {
+		return
+	}
+
+	e.consumeSpace()
+
+	if c := e.consumeToken("="); !c {
+		return
+	}
+
+	e.consumeSpace()
+
+	if c := e.consumeToken("'"); !c {
+		return
+	}
+
+	found := 0
+	escaped := false
+	for {
+		if e.pos+found > len(e.input)-1 {
+			break
+		}
+
+		if escaped {
+			escaped = false
+		} else if e.input[e.pos+found] == '\\' {
+			escaped = true
+		} else if e.input[e.pos+found] == '\'' {
+			break
+		}
+		found += 1
+	}
+	e.pos += found
+
+	if c := e.consumeToken("'"); !c {
+		return
+	}
+}

pkg/snowflake/parser_internal_test.go

@@ -0,0 +1,3 @@
+package snowflake
+
+// Internal tests for ViewSelectStatementExtractor

pkg/snowflake/parser_test.go

@@ -0,0 +1,161 @@
+package snowflake
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestViewSelectStatementExtractor_Extract(t *testing.T) {
+	basic := "create view foo as select * from bar;"
+	caps := "CREATE VIEW FOO AS SELECT * FROM BAR;"
+	parens := "create view foo as (select * from bar);"
+	multiline := `
+create view foo as
+select *
+from bar;`
+
+	multilineComment := `
+create view foo as
+-- comment
+select *
+from bar;`
+
+	secure := "create secure view foo as select * from bar;"
+	replace := "create or replace view foo as select * from bar;"
+	recursive := "create recursive view foo as select * from bar;"
+	ine := "create view if not exists foo as select * from bar;"
+
+	comment := `create view foo comment='asdf' as select * from bar;`
+	commentEscape := `create view foo comment='asdf\'s are fun' as select * from bar;`
+	identifier := `create view "foo"."bar"."bam" comment='asdf\'s are fun' as select * from bar;`
+
+	full := `CREATE SECURE VIEW "rgdxfmnfhh"."PUBLIC"."rgdxfmnfhh" COMMENT = 'Terraform test resource' AS SELECT ROLE_NAME, ROLE_OWNER FROM INFORMATION_SCHEMA.APPLICABLE_ROLES`
+
+	type args struct {
+		input string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr bool
+	}{
+		{"basic", args{basic}, "select * from bar;", false},
+		{"caps", args{caps}, "SELECT * FROM BAR;", false},
+		{"parens", args{parens}, "(select * from bar);", false},
+		{"multiline", args{multiline}, "select *\nfrom bar;", false},
+		{"multilineComment", args{multilineComment}, "-- comment\nselect *\nfrom bar;", false},
+		{"secure", args{secure}, "select * from bar;", false},
+		{"replace", args{replace}, "select * from bar;", false},
+		{"recursive", args{recursive}, "select * from bar;", false},
+		{"ine", args{ine}, "select * from bar;", false},
+		{"comment", args{comment}, "select * from bar;", false},
+		{"commentEscape", args{commentEscape}, "select * from bar;", false},
+		{"identifier", args{identifier}, "select * from bar;", false},
+		{"full", args{full}, "SELECT ROLE_NAME, ROLE_OWNER FROM INFORMATION_SCHEMA.APPLICABLE_ROLES", false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e := NewViewSelectStatementExtractor(tt.args.input)
+			got, err := e.Extract()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ViewSelectStatementExtractor.Extract() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("ViewSelectStatementExtractor.Extract() = '%v', want '%v'", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestViewSelectStatementExtractor_consumeToken(t *testing.T) {
+	type fields struct {
+		input []rune
+		pos   int
+	}
+	type args struct {
+		t string
+	}
+	tests := []struct {
+		name     string
+		fields   fields
+		args     args
+		posAfter int
+	}{
+		{"basic - found", fields{[]rune("foo"), 0}, args{"foo"}, 3},
+		{"basic - not found", fields{[]rune("foo"), 0}, args{"bar"}, 0},
+		{"basic - not found", fields{[]rune("fob"), 0}, args{"foo"}, 0},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e := &ViewSelectStatementExtractor{
+				input: tt.fields.input,
+				pos:   tt.fields.pos,
+			}
+			e.consumeToken(tt.args.t)
+
+			if e.pos != tt.posAfter {
+				t.Errorf("pos after = %v, want %v", e.pos, tt.posAfter)
+			}
+		})
+	}
+}
+
+func TestViewSelectStatementExtractor_consumeSpace(t *testing.T) {
+	type fields struct {
+		input []rune
+		pos   int
+	}
+	tests := []struct {
+		name     string
+		fields   fields
+		posAfter int
+	}{
+		{"simple", fields{[]rune("   foo"), 0}, 3},
+		{"empty", fields{[]rune(""), 0}, 0},
+		{"middle", fields{[]rune("foo \t\n bar"), 3}, 7},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fmt.Println(tt.name)
+			e := &ViewSelectStatementExtractor{
+				input: tt.fields.input,
+				pos:   tt.fields.pos,
+			}
+			e.consumeSpace()
+
+			if e.pos != tt.posAfter {
+				t.Errorf("pos after = %v, want %v", e.pos, tt.posAfter)
+			}
+		})
+	}
+}
+
+func TestViewSelectStatementExtractor_consumeComment(t *testing.T) {
+	type fields struct {
+		input []rune
+		pos   int
+	}
+	tests := []struct {
+		name     string
+		fields   fields
+		posAfter int
+	}{
+		{"basic", fields{[]rune("comment='foo'"), 0}, 13},
+		{"escaped", fields{[]rune(`comment='fo\'o'`), 0}, 15},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e := &ViewSelectStatementExtractor{
+				input: tt.fields.input,
+				pos:   tt.fields.pos,
+			}
+			e.consumeComment()
+
+			if e.pos != tt.posAfter {
+				t.Errorf("pos after = %v, want %v", e.pos, tt.posAfter)
+			}
+		})
+	}
+}