package tui

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/charmbracelet/bubbles/spinner"
	"github.com/charmbracelet/bubbles/textarea"
	"github.com/charmbracelet/bubbles/viewport"
	tea "github.com/charmbracelet/bubbletea"

	"nub/internal/agent"
	"nub/internal/llm"
	"nub/internal/session"
	"nub/internal/tool"
)

func enterKey() tea.KeyMsg  { return tea.KeyMsg{Type: tea.KeyEnter} }
func escKey() tea.KeyMsg    { return tea.KeyMsg{Type: tea.KeyEsc} }
func deleteKey() tea.KeyMsg { return tea.KeyMsg{Type: tea.KeyDelete} }
func yKey() tea.KeyMsg      { return tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune("y")} }
func nKey() tea.KeyMsg      { return tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune("n")} }

func newTestModelWithStore(t *testing.T) *Model {
	t.Helper()
	dir := t.TempDir()
	store, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { store.Close() })

	return &Model{
		ctx:      context.Background(),
		store:    store,
		textarea: textarea.New(),
		viewport: viewport.New(80, 20),
		spinner:  spinner.New(),
	}
}

func textMsg(role llm.Role, text string) llm.Message {
	return llm.Message{Role: role, Content: []llm.Block{{Kind: llm.KindText, Text: text}}}
}

func findItem(items []listItem, id string) int {
	for i, it := range items {
		if it.id == id {
			return i
		}
	}
	return -1
}

func TestCmdOpenTree_MarksCurrentHead(t *testing.T) {
	m := newTestModelWithStore(t)

	n1 := session.NewNode("", textMsg(llm.RoleUser, "first"), session.NodeMeta{})
	if err := m.store.Append(n1); err != nil {
		t.Fatal(err)
	}
	n2 := session.NewNode(n1.ID, textMsg(llm.RoleAssistant, "second"), session.NodeMeta{})
	if err := m.store.Append(n2); err != nil {
		t.Fatal(err)
	}

	m.cmdOpenTree()
	if m.modal == nil {
		t.Fatal("expected a modal to be opened")
	}
	if len(m.modal.items) != 2 {
		t.Fatalf("got %d items, want 2", len(m.modal.items))
	}
	if m.modal.items[m.modal.cursor].id != n2.ID {
		t.Errorf("cursor should default to the current head (%s), got %s", n2.ID, m.modal.items[m.modal.cursor].id)
	}
}

func TestHandleModalKey_EnterBranchesToSelectedNode(t *testing.T) {
	m := newTestModelWithStore(t)

	n1 := session.NewNode("", textMsg(llm.RoleUser, "first"), session.NodeMeta{})
	if err := m.store.Append(n1); err != nil {
		t.Fatal(err)
	}
	n2 := session.NewNode(n1.ID, textMsg(llm.RoleAssistant, "second"), session.NodeMeta{})
	if err := m.store.Append(n2); err != nil {
		t.Fatal(err)
	}

	m.cmdOpenTree()
	m.modal.cursor = findItem(m.modal.items, n1.ID) // n1 auswählen, nicht den aktuellen Head n2

	m.handleModalKey(enterKey())

	if m.modal != nil {
		t.Error("expected modal to close after selection")
	}
	if m.store.Head != n1.ID {
		t.Errorf("head = %s, want %s (branch to selected node)", m.store.Head, n1.ID)
	}
}

func TestHandleModalKey_EscClosesWithoutBranching(t *testing.T) {
	m := newTestModelWithStore(t)
	n1 := session.NewNode("", textMsg(llm.RoleUser, "first"), session.NodeMeta{})
	if err := m.store.Append(n1); err != nil {
		t.Fatal(err)
	}
	originalHead := m.store.Head
	m.cmdOpenTree()

	m.handleModalKey(escKey())

	if m.modal != nil {
		t.Error("expected modal to close on esc")
	}
	if m.store.Head != originalHead {
		t.Error("esc must not change the head")
	}
}

func newTestModelForSessions(t *testing.T, dir string, store *session.Store) *Model {
	t.Helper()
	return &Model{
		ctx:      context.Background(),
		store:    store,
		loop:     &agent.Loop{Env: tool.Env{RepoRoot: dir}},
		textarea: textarea.New(),
		viewport: viewport.New(80, 20),
		spinner:  spinner.New(),
	}
}

func TestCmdSessions_ListsAllAndMarksActive(t *testing.T) {
	dir := t.TempDir()
	active, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { active.Close() })
	other, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	other.Close()

	m := newTestModelForSessions(t, dir, active)
	m.cmdSessions()

	if m.modal == nil {
		t.Fatal("expected a modal to be opened")
	}
	if len(m.modal.items) != 2 {
		t.Fatalf("got %d items, want 2", len(m.modal.items))
	}
	idx := findItem(m.modal.items, active.ID)
	if idx == -1 {
		t.Fatal("active session missing from list")
	}
	if !m.modal.items[idx].protect || m.modal.items[idx].marker != "(aktiv)" {
		t.Errorf("active session item = %+v, want protected and marked", m.modal.items[idx])
	}
	if m.modal.cursor != idx {
		t.Errorf("cursor = %d, want %d (default to active session)", m.modal.cursor, idx)
	}
}

func TestHandleModalKey_DeleteRequiresConfirmation(t *testing.T) {
	dir := t.TempDir()
	active, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { active.Close() })
	other, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	other.Close()

	m := newTestModelForSessions(t, dir, active)
	m.cmdSessions()
	m.modal.cursor = findItem(m.modal.items, other.ID)

	m.handleModalKey(deleteKey())
	if !m.modal.confirmDelete {
		t.Fatal("expected Del to arm a confirmation, not delete immediately")
	}
	if _, err := session.List(dir); err != nil {
		t.Fatal(err)
	}

	m.handleModalKey(nKey())
	if m.modal == nil || m.modal.confirmDelete {
		t.Error("expected 'n' to cancel the confirmation without closing the modal")
	}
	infos, err := session.List(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(infos) != 2 {
		t.Errorf("declining the confirmation must not delete anything, got %d sessions", len(infos))
	}
}

func TestHandleModalKey_DeleteConfirmedRemovesSession(t *testing.T) {
	dir := t.TempDir()
	active, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { active.Close() })
	other, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	other.Close()

	m := newTestModelForSessions(t, dir, active)
	m.cmdSessions()
	m.modal.cursor = findItem(m.modal.items, other.ID)
	m.handleModalKey(deleteKey())
	m.handleModalKey(yKey())

	if m.modal != nil {
		t.Error("expected modal to close after a confirmed delete")
	}
	infos, err := session.List(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(infos) != 1 || infos[0].ID != active.ID {
		t.Errorf("expected only the active session left, got %+v", infos)
	}
}

func TestHandleModalKey_CannotDeleteActiveSession(t *testing.T) {
	dir := t.TempDir()
	active, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { active.Close() })

	m := newTestModelForSessions(t, dir, active)
	m.cmdSessions()
	// Nur eine Session vorhanden -> Cursor steht zwangsläufig auf der aktiven.

	m.handleModalKey(deleteKey())
	if m.modal.confirmDelete {
		t.Error("expected the active session to be protected from even arming a delete")
	}

	infos, err := session.List(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(infos) != 1 {
		t.Error("active session must not be deletable")
	}
}

func TestCmdInit_CreatesFilesAndReportsResult(t *testing.T) {
	dir := t.TempDir()
	store, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { store.Close() })

	m := newTestModelForSessions(t, dir, store)
	m.runCommand("/init")

	if len(m.entries) != 1 || m.entries[0].kind != entryCommand {
		t.Fatalf("entries = %+v, want a single entryCommand", m.entries)
	}
	text := m.entries[0].text
	if !strings.Contains(text, "angelegt") {
		t.Errorf("expected the report to mention what was created, got: %q", text)
	}

	if _, err := os.Stat(filepath.Join(dir, ".nub", "config.toml")); err != nil {
		t.Errorf(".nub/config.toml missing: %v", err)
	}
	if _, err := os.Stat(filepath.Join(dir, "AGENTS.md")); err != nil {
		t.Errorf("AGENTS.md missing: %v", err)
	}
}

func TestCmdInit_SecondRunSkipsExistingFiles(t *testing.T) {
	dir := t.TempDir()
	store, err := session.Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { store.Close() })

	m := newTestModelForSessions(t, dir, store)
	m.runCommand("/init")
	m.entries = nil
	m.runCommand("/init")

	if len(m.entries) != 1 {
		t.Fatalf("entries = %+v", m.entries)
	}
	if !strings.Contains(m.entries[0].text, "übersprungen") {
		t.Errorf("expected the second run to report skipped files, got: %q", m.entries[0].text)
	}
}