From 77f2e2847d8c171563e824cfadc402e8001882ac Mon Sep 17 00:00:00 2001
From: Adam Scarr <adam@vektah.net>
Date: Tue, 13 Nov 2018 20:42:46 +1100
Subject: [PATCH] Start moving import management to templates

---
 codegen/templates/import.go                   | 96 +++++++++++++++++++
 codegen/templates/import_test.go              | 56 +++++++++++
 codegen/templates/testdata/a/bar/bar.go       |  1 +
 codegen/templates/testdata/b/bar/bar.go       |  1 +
 .../testdata/pkg_mismatch/turtles.go          |  1 +
 5 files changed, 155 insertions(+)
 create mode 100644 codegen/templates/import.go
 create mode 100644 codegen/templates/import_test.go
 create mode 100644 codegen/templates/testdata/a/bar/bar.go
 create mode 100644 codegen/templates/testdata/b/bar/bar.go
 create mode 100644 codegen/templates/testdata/pkg_mismatch/turtles.go

diff --git a/codegen/templates/import.go b/codegen/templates/import.go
new file mode 100644
index 00000000000..29aa6f90dbf
--- /dev/null
+++ b/codegen/templates/import.go
@@ -0,0 +1,96 @@
+package templates
+
+import (
+	"fmt"
+	"go/build"
+	"strconv"
+
+	"github.com/99designs/gqlgen/internal/gopath"
+)
+
+type Import struct {
+	Name  string
+	Path  string
+	Alias string
+}
+
+type Imports struct {
+	imports []*Import
+	destDir string
+}
+
+func (i *Import) String() string {
+	if i.Alias == i.Name {
+		return strconv.Quote(i.Path)
+	}
+
+	return i.Alias + " " + strconv.Quote(i.Path)
+}
+
+func (s *Imports) String() string {
+	res := ""
+	for i, imp := range s.imports {
+		if i != 0 {
+			res += "\n"
+		}
+		res += imp.String()
+	}
+	return res
+}
+
+func (s *Imports) Lookup(path string) string {
+	if path == "" {
+		return ""
+	}
+
+	// if we are referencing our own package we dont need an import
+	if gopath.MustDir2Import(s.destDir) == path {
+		return ""
+	}
+
+	if existing := s.findByPath(path); existing != nil {
+		return existing.Alias
+	}
+
+	pkg, err := build.Default.Import(path, s.destDir, 0)
+	if err != nil {
+		panic(err)
+	}
+
+	imp := &Import{
+		Name: pkg.Name,
+		Path: path,
+	}
+	s.imports = append(s.imports, imp)
+
+	alias := imp.Name
+	i := 1
+	for s.findByAlias(alias) != nil {
+		alias = imp.Name + strconv.Itoa(i)
+		i++
+		if i > 10 {
+			panic(fmt.Errorf("too many collisions, last attempt was %s", alias))
+		}
+	}
+	imp.Alias = alias
+
+	return imp.Alias
+}
+
+func (s Imports) findByPath(importPath string) *Import {
+	for _, imp := range s.imports {
+		if imp.Path == importPath {
+			return imp
+		}
+	}
+	return nil
+}
+
+func (s Imports) findByAlias(alias string) *Import {
+	for _, imp := range s.imports {
+		if imp.Alias == alias {
+			return imp
+		}
+	}
+	return nil
+}
diff --git a/codegen/templates/import_test.go b/codegen/templates/import_test.go
new file mode 100644
index 00000000000..16ec405dec5
--- /dev/null
+++ b/codegen/templates/import_test.go
@@ -0,0 +1,56 @@
+package templates
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestImports(t *testing.T) {
+	wd, err := os.Getwd()
+	require.NoError(t, err)
+
+	aBar := "github.com/99designs/gqlgen/codegen/templates/testdata/a/bar"
+	bBar := "github.com/99designs/gqlgen/codegen/templates/testdata/b/bar"
+	mismatch := "github.com/99designs/gqlgen/codegen/templates/testdata/pkg_mismatch"
+
+	t.Run("multiple lookups is ok", func(t *testing.T) {
+		a := Imports{destDir: wd}
+
+		require.Equal(t, "bar", a.Lookup(aBar))
+		require.Equal(t, "bar", a.Lookup(aBar))
+	})
+
+	t.Run("duplicates are decollisioned", func(t *testing.T) {
+		a := Imports{destDir: wd}
+
+		require.Equal(t, "bar", a.Lookup(aBar))
+		require.Equal(t, "bar1", a.Lookup(bBar))
+
+		t.Run("additionial calls get decollisioned name", func(t *testing.T) {
+			require.Equal(t, "bar1", a.Lookup(bBar))
+		})
+	})
+
+	t.Run("package name defined in code will be used", func(t *testing.T) {
+		a := Imports{destDir: wd}
+
+		require.Equal(t, "turtles", a.Lookup(mismatch))
+	})
+
+	t.Run("string printing for import block", func(t *testing.T) {
+		a := Imports{destDir: wd}
+		a.Lookup(aBar)
+		a.Lookup(bBar)
+		a.Lookup(mismatch)
+
+		require.Equal(
+			t,
+			`"github.com/99designs/gqlgen/codegen/templates/testdata/a/bar"
+bar1 "github.com/99designs/gqlgen/codegen/templates/testdata/b/bar"
+"github.com/99designs/gqlgen/codegen/templates/testdata/pkg_mismatch"`,
+			a.String(),
+		)
+	})
+}
diff --git a/codegen/templates/testdata/a/bar/bar.go b/codegen/templates/testdata/a/bar/bar.go
new file mode 100644
index 00000000000..ddac0faf273
--- /dev/null
+++ b/codegen/templates/testdata/a/bar/bar.go
@@ -0,0 +1 @@
+package bar
diff --git a/codegen/templates/testdata/b/bar/bar.go b/codegen/templates/testdata/b/bar/bar.go
new file mode 100644
index 00000000000..ddac0faf273
--- /dev/null
+++ b/codegen/templates/testdata/b/bar/bar.go
@@ -0,0 +1 @@
+package bar
diff --git a/codegen/templates/testdata/pkg_mismatch/turtles.go b/codegen/templates/testdata/pkg_mismatch/turtles.go
new file mode 100644
index 00000000000..a90e7072717
--- /dev/null
+++ b/codegen/templates/testdata/pkg_mismatch/turtles.go
@@ -0,0 +1 @@
+package turtles