// Copyright (c) The OpenTofu Authors
// SPDX-License-Identifier: MPL-2.0
// Copyright (c) 2023 HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0

package refactoring

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"runtime"
	"sort"
	"testing"

	"github.com/google/go-cmp/cmp"

	"github.com/opentofu/opentofu/internal/addrs"
	"github.com/opentofu/opentofu/internal/states"
	"github.com/opentofu/opentofu/internal/tfdiags"
)

// Changes line endings from Windows-style ('\r\n') to Unix-style ('\n').
func normaliseLineEndings(filename string) ([]byte, error) {
	originalContent, err := os.ReadFile(filename)
	if err != nil {
		return nil, fmt.Errorf("error reading file %s: %w", filename, err)
	}

	// Replace all occurrences of '\r\n' with '\n'
	normalisedContent := bytes.ReplaceAll(originalContent, []byte("\r\n"), []byte("\n"))

	if !bytes.Equal(originalContent, normalisedContent) {
		err = os.WriteFile(filename, normalisedContent, 0600)
		if err != nil {
			return nil, fmt.Errorf("error writing file %s: %w", filename, err)
		}
	}

	return originalContent, nil
}

func TestImpliedMoveStatements(t *testing.T) {
	// Normalise file content for cross-platform compatibility
	if runtime.GOOS == "windows" {
		file1 := "testdata/move-statement-implied/move-statement-implied.tf"
		file2 := "testdata/move-statement-implied/child/move-statement-implied.tf"
		originalContent, err := normaliseLineEndings(file1)
		if err != nil {
			t.Errorf("Error normalising line endings %v", err)
		}
		originalContentChild, err := normaliseLineEndings(file2)
		if err != nil {
			t.Errorf("Error normalising line endings %v", err)
		}

		// Restore original file content after test completion
		t.Cleanup(func() {
			err1 := os.WriteFile(file1, originalContent, 0600)
			if err1 != nil {
				t.Error()
			}
			err = os.WriteFile(file2, originalContentChild, 0600)
			if err != nil {
				t.Error()
			}
		},
		)
	}

	resourceAddr := func(name string) addrs.AbsResource {
		return addrs.Resource{
			Mode: addrs.ManagedResourceMode,
			Type: "foo",
			Name: name,
		}.Absolute(addrs.RootModuleInstance)
	}

	nestedResourceAddr := func(mod, name string) addrs.AbsResource {
		return addrs.Resource{
			Mode: addrs.ManagedResourceMode,
			Type: "foo",
			Name: name,
		}.Absolute(addrs.RootModuleInstance.Child(mod, addrs.NoKey))
	}

	instObjState := func() *states.ResourceInstanceObjectSrc {
		return &states.ResourceInstanceObjectSrc{}
	}
	providerAddr := addrs.AbsProviderConfig{
		Module:   addrs.RootModule,
		Provider: addrs.MustParseProviderSourceString("hashicorp/foo"),
	}

	rootCfg, _ := loadRefactoringFixture(t, "testdata/move-statement-implied")
	prevRunState := states.BuildState(func(s *states.SyncState) {
		s.SetResourceInstanceCurrent(
			resourceAddr("formerly_count").Instance(addrs.IntKey(0)),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("formerly_count").Instance(addrs.IntKey(1)),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("now_count").Instance(addrs.NoKey),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("formerly_count_explicit").Instance(addrs.IntKey(0)),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("formerly_count_explicit").Instance(addrs.IntKey(1)),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("now_count_explicit").Instance(addrs.NoKey),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("now_for_each_formerly_count").Instance(addrs.IntKey(0)),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("now_for_each_formerly_no_count").Instance(addrs.NoKey),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)

		// This "ambiguous" resource is representing a rare but possible
		// situation where we end up having a mixture of different index
		// types in the state at the same time. The main way to get into
		// this state would be to remove "count = 1" and then have the
		// provider fail to destroy the zero-key instance even though we
		// already created the no-key instance. Users can also get here
		// by using "tofu state mv" in weird ways.
		s.SetResourceInstanceCurrent(
			resourceAddr("ambiguous").Instance(addrs.NoKey),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			resourceAddr("ambiguous").Instance(addrs.IntKey(0)),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)

		// Add two resource nested in a module to ensure we find these
		// recursively.
		s.SetResourceInstanceCurrent(
			nestedResourceAddr("child", "formerly_count").Instance(addrs.IntKey(0)),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
		s.SetResourceInstanceCurrent(
			nestedResourceAddr("child", "now_count").Instance(addrs.NoKey),
			instObjState(),
			providerAddr,
			addrs.NoKey,
		)
	})

	explicitStmts := FindMoveStatements(rootCfg)
	got := ImpliedMoveStatements(rootCfg, prevRunState, explicitStmts)
	want := []MoveStatement{
		{
			From:    addrs.ImpliedMoveStatementEndpoint(resourceAddr("formerly_count").Instance(addrs.IntKey(0)), tfdiags.SourceRange{}),
			To:      addrs.ImpliedMoveStatementEndpoint(resourceAddr("formerly_count").Instance(addrs.NoKey), tfdiags.SourceRange{}),
			Implied: true,
			DeclRange: tfdiags.SourceRange{
				Filename: filepath.Join("testdata", "move-statement-implied", "move-statement-implied.tf"),
				Start:    tfdiags.SourcePos{Line: 5, Column: 1, Byte: 180},
				End:      tfdiags.SourcePos{Line: 5, Column: 32, Byte: 211},
			},
		},

		// Found implied moves in a nested module, ignoring the explicit moves
		{
			From:    addrs.ImpliedMoveStatementEndpoint(nestedResourceAddr("child", "formerly_count").Instance(addrs.IntKey(0)), tfdiags.SourceRange{}),
			To:      addrs.ImpliedMoveStatementEndpoint(nestedResourceAddr("child", "formerly_count").Instance(addrs.NoKey), tfdiags.SourceRange{}),
			Implied: true,
			DeclRange: tfdiags.SourceRange{
				Filename: filepath.Join("testdata", "move-statement-implied", "child", "move-statement-implied.tf"),
				Start:    tfdiags.SourcePos{Line: 5, Column: 1, Byte: 180},
				End:      tfdiags.SourcePos{Line: 5, Column: 32, Byte: 211},
			},
		},

		{
			From:    addrs.ImpliedMoveStatementEndpoint(resourceAddr("now_count").Instance(addrs.NoKey), tfdiags.SourceRange{}),
			To:      addrs.ImpliedMoveStatementEndpoint(resourceAddr("now_count").Instance(addrs.IntKey(0)), tfdiags.SourceRange{}),
			Implied: true,
			DeclRange: tfdiags.SourceRange{
				Filename: filepath.Join("testdata", "move-statement-implied", "move-statement-implied.tf"),
				Start:    tfdiags.SourcePos{Line: 10, Column: 11, Byte: 282},
				End:      tfdiags.SourcePos{Line: 10, Column: 12, Byte: 283},
			},
		},

		// Found implied moves in a nested module, ignoring the explicit moves
		{
			From:    addrs.ImpliedMoveStatementEndpoint(nestedResourceAddr("child", "now_count").Instance(addrs.NoKey), tfdiags.SourceRange{}),
			To:      addrs.ImpliedMoveStatementEndpoint(nestedResourceAddr("child", "now_count").Instance(addrs.IntKey(0)), tfdiags.SourceRange{}),
			Implied: true,
			DeclRange: tfdiags.SourceRange{
				Filename: filepath.Join("testdata", "move-statement-implied", "child", "move-statement-implied.tf"),
				Start:    tfdiags.SourcePos{Line: 10, Column: 11, Byte: 282},
				End:      tfdiags.SourcePos{Line: 10, Column: 12, Byte: 283},
			},
		},

		// We generate foo.ambiguous[0] to foo.ambiguous here, even though
		// there's already a foo.ambiguous in the state, because it's the
		// responsibility of the later ApplyMoves step to deal with the
		// situation where an object wants to move into an address already
		// occupied by another object.
		{
			From:    addrs.ImpliedMoveStatementEndpoint(resourceAddr("ambiguous").Instance(addrs.IntKey(0)), tfdiags.SourceRange{}),
			To:      addrs.ImpliedMoveStatementEndpoint(resourceAddr("ambiguous").Instance(addrs.NoKey), tfdiags.SourceRange{}),
			Implied: true,
			DeclRange: tfdiags.SourceRange{
				Filename: filepath.Join("testdata", "move-statement-implied", "move-statement-implied.tf"),
				Start:    tfdiags.SourcePos{Line: 46, Column: 1, Byte: 806},
				End:      tfdiags.SourcePos{Line: 46, Column: 27, Byte: 832},
			},
		},
	}

	sort.Slice(got, func(i, j int) bool {
		// This is just an arbitrary sort to make the result consistent
		// regardless of what order the ImpliedMoveStatements function
		// visits the entries in the state/config.
		return got[i].DeclRange.Start.Line < got[j].DeclRange.Start.Line
	})

	if diff := cmp.Diff(want, got); diff != "" {
		t.Errorf("wrong result\n%s", diff)
	}
}