package daemon

import (
	"context"
	"io"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"banger/internal/api"
	"banger/internal/model"
)

// exportGuestClient is a scriptable fake for RunScriptOutput used in export tests.
// Each call to RunScriptOutput returns the next response from the queue.
type exportGuestClient struct {
	responses []exportGuestResponse
	scripts   []string
	callIndex int
}

type exportGuestResponse struct {
	output []byte
	err    error
}

func (e *exportGuestClient) Close() error { return nil }

func (e *exportGuestClient) RunScript(_ context.Context, _ string, _ io.Writer) error {
	return nil
}

func (e *exportGuestClient) RunScriptOutput(_ context.Context, script string) ([]byte, error) {
	e.scripts = append(e.scripts, script)
	if e.callIndex >= len(e.responses) {
		return nil, nil
	}
	r := e.responses[e.callIndex]
	e.callIndex++
	return r.output, r.err
}

func (e *exportGuestClient) UploadFile(_ context.Context, _ string, _ os.FileMode, _ []byte, _ io.Writer) error {
	return nil
}

func (e *exportGuestClient) StreamTar(_ context.Context, _ string, _ string, _ io.Writer) error {
	return nil
}

func (e *exportGuestClient) StreamTarEntries(_ context.Context, _ string, _ []string, _ string, _ io.Writer) error {
	return nil
}

func newExportTestDaemonStore(t *testing.T, fake *exportGuestClient) *Daemon {
	t.Helper()
	db := openDaemonStore(t)
	d := &Daemon{
		store:  db,
		config: model.DaemonConfig{SSHKeyPath: filepath.Join(t.TempDir(), "id_ed25519")},
		logger: slog.New(slog.NewTextHandler(io.Discard, nil)),
	}
	d.guestDial = func(_ context.Context, _ string, _ string) (guestSSHClient, error) {
		return fake, nil
	}
	return d
}

func TestExportVMWorkspace_HappyPath(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	apiSock := filepath.Join(t.TempDir(), "fc.sock")
	firecracker := startFakeFirecracker(t, apiSock)

	vm := testVM("exportbox", "image-export", "172.16.0.100")
	vm.State = model.VMStateRunning
	vm.Runtime.State = model.VMStateRunning
	vm.Runtime.PID = firecracker.Process.Pid
	vm.Runtime.APISockPath = apiSock

	patch := []byte("diff --git a/file.go b/file.go\nindex 0000000..1111111 100644\n")
	names := []byte("file.go\n")

	fake := &exportGuestClient{
		responses: []exportGuestResponse{
			{output: patch},
			{output: names},
		},
	}
	d := newExportTestDaemonStore(t, fake)
	upsertDaemonVM(t, ctx, d.store, vm)

	result, err := d.ExportVMWorkspace(ctx, api.WorkspaceExportParams{
		IDOrName:  vm.Name,
		GuestPath: "/root/repo",
	})
	if err != nil {
		t.Fatalf("ExportVMWorkspace: %v", err)
	}
	if !result.HasChanges {
		t.Fatal("HasChanges = false, want true")
	}
	if string(result.Patch) != string(patch) {
		t.Fatalf("Patch = %q, want %q", result.Patch, patch)
	}
	if result.GuestPath != "/root/repo" {
		t.Fatalf("GuestPath = %q, want /root/repo", result.GuestPath)
	}
	if len(result.ChangedFiles) != 1 || result.ChangedFiles[0] != "file.go" {
		t.Fatalf("ChangedFiles = %v, want [file.go]", result.ChangedFiles)
	}
	if fake.callIndex != 2 {
		t.Fatalf("RunScriptOutput call count = %d, want 2", fake.callIndex)
	}
	// No base_commit provided: diff ref must be HEAD.
	for _, script := range fake.scripts {
		if !strings.Contains(script, "HEAD") {
			t.Fatalf("script missing HEAD ref: %q", script)
		}
	}
	if result.BaseCommit != "HEAD" {
		t.Fatalf("BaseCommit = %q, want HEAD", result.BaseCommit)
	}
}

func TestExportVMWorkspace_WithBaseCommit(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	apiSock := filepath.Join(t.TempDir(), "fc.sock")
	firecracker := startFakeFirecracker(t, apiSock)

	vm := testVM("exportbox-base", "image-export", "172.16.0.105")
	vm.State = model.VMStateRunning
	vm.Runtime.State = model.VMStateRunning
	vm.Runtime.PID = firecracker.Process.Pid
	vm.Runtime.APISockPath = apiSock

	// Simulate: worker committed inside the VM. Without base_commit the diff
	// against the new HEAD would be empty. With base_commit we capture
	// everything since the original checkout.
	patch := []byte("diff --git a/worker.go b/worker.go\nindex 0000000..abcdef 100644\n")
	names := []byte("worker.go\n")

	fake := &exportGuestClient{
		responses: []exportGuestResponse{
			{output: patch},
			{output: names},
		},
	}
	d := newExportTestDaemonStore(t, fake)
	upsertDaemonVM(t, ctx, d.store, vm)

	const prepareCommit = "abc1234deadbeef"
	result, err := d.ExportVMWorkspace(ctx, api.WorkspaceExportParams{
		IDOrName:   vm.Name,
		BaseCommit: prepareCommit,
	})
	if err != nil {
		t.Fatalf("ExportVMWorkspace: %v", err)
	}
	if !result.HasChanges {
		t.Fatal("HasChanges = false, want true")
	}
	if result.BaseCommit != prepareCommit {
		t.Fatalf("BaseCommit = %q, want %q", result.BaseCommit, prepareCommit)
	}
	// Both scripts must reference the caller-supplied commit, not HEAD.
	for _, script := range fake.scripts {
		if strings.Contains(script, " HEAD") {
			t.Fatalf("script used HEAD instead of base_commit: %q", script)
		}
		if !strings.Contains(script, prepareCommit) {
			t.Fatalf("script missing base_commit %q: %q", prepareCommit, script)
		}
	}
}

func TestExportVMWorkspace_BaseCommitFallsBackToHEAD(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	apiSock := filepath.Join(t.TempDir(), "fc.sock")
	firecracker := startFakeFirecracker(t, apiSock)

	vm := testVM("exportbox-nobase", "image-export", "172.16.0.106")
	vm.State = model.VMStateRunning
	vm.Runtime.State = model.VMStateRunning
	vm.Runtime.PID = firecracker.Process.Pid
	vm.Runtime.APISockPath = apiSock

	fake := &exportGuestClient{
		responses: []exportGuestResponse{
			{output: nil},
			{output: nil},
		},
	}
	d := newExportTestDaemonStore(t, fake)
	upsertDaemonVM(t, ctx, d.store, vm)

	result, err := d.ExportVMWorkspace(ctx, api.WorkspaceExportParams{
		IDOrName:   vm.Name,
		BaseCommit: "", // omitted
	})
	if err != nil {
		t.Fatalf("ExportVMWorkspace: %v", err)
	}
	if result.BaseCommit != "HEAD" {
		t.Fatalf("BaseCommit = %q, want HEAD when not supplied", result.BaseCommit)
	}
	for _, script := range fake.scripts {
		if !strings.Contains(script, "HEAD") {
			t.Fatalf("script missing HEAD fallback: %q", script)
		}
	}
}

func TestExportVMWorkspace_NoChanges(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	apiSock := filepath.Join(t.TempDir(), "fc.sock")
	firecracker := startFakeFirecracker(t, apiSock)

	vm := testVM("exportbox-empty", "image-export", "172.16.0.101")
	vm.State = model.VMStateRunning
	vm.Runtime.State = model.VMStateRunning
	vm.Runtime.PID = firecracker.Process.Pid
	vm.Runtime.APISockPath = apiSock

	// Both scripts return empty output (no changes).
	fake := &exportGuestClient{
		responses: []exportGuestResponse{
			{output: nil},
			{output: nil},
		},
	}
	d := newExportTestDaemonStore(t, fake)
	upsertDaemonVM(t, ctx, d.store, vm)

	result, err := d.ExportVMWorkspace(ctx, api.WorkspaceExportParams{
		IDOrName: vm.Name,
	})
	if err != nil {
		t.Fatalf("ExportVMWorkspace: %v", err)
	}
	if result.HasChanges {
		t.Fatal("HasChanges = true, want false")
	}
	if len(result.Patch) != 0 {
		t.Fatalf("Patch = %q, want empty", result.Patch)
	}
	if len(result.ChangedFiles) != 0 {
		t.Fatalf("ChangedFiles = %v, want empty", result.ChangedFiles)
	}
}

func TestExportVMWorkspace_DefaultGuestPath(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	apiSock := filepath.Join(t.TempDir(), "fc.sock")
	firecracker := startFakeFirecracker(t, apiSock)

	vm := testVM("exportbox-default", "image-export", "172.16.0.102")
	vm.State = model.VMStateRunning
	vm.Runtime.State = model.VMStateRunning
	vm.Runtime.PID = firecracker.Process.Pid
	vm.Runtime.APISockPath = apiSock

	fake := &exportGuestClient{
		responses: []exportGuestResponse{
			{output: nil},
			{output: nil},
		},
	}
	d := newExportTestDaemonStore(t, fake)
	upsertDaemonVM(t, ctx, d.store, vm)

	// GuestPath omitted — should default to /root/repo.
	result, err := d.ExportVMWorkspace(ctx, api.WorkspaceExportParams{
		IDOrName: vm.Name,
	})
	if err != nil {
		t.Fatalf("ExportVMWorkspace: %v", err)
	}
	if result.GuestPath != "/root/repo" {
		t.Fatalf("GuestPath = %q, want /root/repo", result.GuestPath)
	}
}

func TestExportVMWorkspace_VMNotRunning(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	vm := testVM("exportbox-stopped", "image-export", "172.16.0.103")
	vm.State = model.VMStateStopped

	fake := &exportGuestClient{}
	d := newExportTestDaemonStore(t, fake)
	upsertDaemonVM(t, ctx, d.store, vm)

	_, err := d.ExportVMWorkspace(ctx, api.WorkspaceExportParams{
		IDOrName: vm.Name,
	})
	if err == nil || !strings.Contains(err.Error(), "not running") {
		t.Fatalf("error = %v, want 'not running' error", err)
	}
	if fake.callIndex != 0 {
		t.Fatal("RunScriptOutput should not be called when VM is not running")
	}
}

func TestExportVMWorkspace_MultipleChangedFiles(t *testing.T) {
	t.Parallel()
	ctx := context.Background()

	apiSock := filepath.Join(t.TempDir(), "fc.sock")
	firecracker := startFakeFirecracker(t, apiSock)

	vm := testVM("exportbox-multi", "image-export", "172.16.0.104")
	vm.State = model.VMStateRunning
	vm.Runtime.State = model.VMStateRunning
	vm.Runtime.PID = firecracker.Process.Pid
	vm.Runtime.APISockPath = apiSock

	patch := []byte("diff --git a/a.go b/a.go\n--- a/a.go\n+++ b/a.go\n")
	names := []byte("a.go\nb.go\nnew/file.go\n")

	fake := &exportGuestClient{
		responses: []exportGuestResponse{
			{output: patch},
			{output: names},
		},
	}
	d := newExportTestDaemonStore(t, fake)
	upsertDaemonVM(t, ctx, d.store, vm)

	result, err := d.ExportVMWorkspace(ctx, api.WorkspaceExportParams{
		IDOrName: vm.Name,
	})
	if err != nil {
		t.Fatalf("ExportVMWorkspace: %v", err)
	}
	if len(result.ChangedFiles) != 3 {
		t.Fatalf("ChangedFiles = %v, want 3 entries", result.ChangedFiles)
	}
	want := []string{"a.go", "b.go", "new/file.go"}
	for i, f := range want {
		if result.ChangedFiles[i] != f {
			t.Fatalf("ChangedFiles[%d] = %q, want %q", i, result.ChangedFiles[i], f)
		}
	}
}