package views

import (
	"fmt"
	"strings"

	"github.com/charmbracelet/bubbles/textinput"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"

	"task/internal/project"
)

// ProjectEdit field indices.
const (
	FieldRemoteURL = iota
	FieldToken
	FieldProjectKey
	ProjectEditFieldCount
)

// ProjectEditStyles styles the project edit form.
type ProjectEditStyles struct {
	Label   lipgloss.Style
	Focused lipgloss.Style
	Blurred lipgloss.Style
	Hint    lipgloss.Style
	Title   lipgloss.Style
}

// DefaultProjectEditStyles returns sensible defaults.
func DefaultProjectEditStyles() ProjectEditStyles {
	return ProjectEditStyles{
		Label:   lipgloss.NewStyle().Foreground(lipgloss.Color("245")),
		Focused: lipgloss.NewStyle().Foreground(lipgloss.Color("205")),
		Blurred: lipgloss.NewStyle().Foreground(lipgloss.Color("240")),
		Hint:    lipgloss.NewStyle().Foreground(lipgloss.Color("241")),
		Title:   lipgloss.NewStyle().Bold(true),
	}
}

// ProjectEditForm is a multi-field editor for YouTrack project settings.
type ProjectEditForm struct {
	ProjectID    string
	Inputs       []textinput.Model
	Focus        int
	Styles       ProjectEditStyles
	Width        int
	hadToken     bool
	tokenChanged bool
}

// NewProjectEditForm builds a form prefilled from meta.
func NewProjectEditForm(projectID string, meta project.Meta, width int) ProjectEditForm {
	styles := DefaultProjectEditStyles()
	inputs := make([]textinput.Model, ProjectEditFieldCount)

	mk := func(placeholder string, charLimit int, password bool) textinput.Model {
		ti := textinput.New()
		ti.Placeholder = placeholder
		ti.CharLimit = charLimit
		ti.Width = max(20, width-4)
		if password {
			ti.EchoMode = textinput.EchoPassword
			ti.EchoCharacter = '•'
		}
		return ti
	}

	inputs[FieldRemoteURL] = mk("https://youtrack.example.com", 256, false)
	inputs[FieldToken] = mk("permanent token", 512, true)
	inputs[FieldProjectKey] = mk("PROJ", 64, false)

	hadToken := false
	if meta.YouTrack != nil {
		yt := meta.YouTrack
		inputs[FieldRemoteURL].SetValue(yt.BaseURL)
		inputs[FieldProjectKey].SetValue(yt.ProjectKey)
		if yt.Token != "" {
			hadToken = true
			inputs[FieldToken].Placeholder = "(unchanged — type to replace)"
		}
	}

	f := ProjectEditForm{
		ProjectID: projectID,
		Inputs:    inputs,
		Focus:     FieldRemoteURL,
		Styles:    styles,
		Width:     width,
		hadToken:  hadToken,
	}
	f.focusIndex(FieldRemoteURL)
	return f
}

func (f *ProjectEditForm) focusIndex(i int) {
	f.Focus = i
	for idx := range f.Inputs {
		if idx == i {
			f.Inputs[idx].Focus()
			f.Inputs[idx].PromptStyle = f.Styles.Focused
			f.Inputs[idx].TextStyle = f.Styles.Focused
		} else {
			f.Inputs[idx].Blur()
			f.Inputs[idx].PromptStyle = f.Styles.Blurred
			f.Inputs[idx].TextStyle = f.Styles.Blurred
		}
	}
}

// NextField moves focus to the next field.
func (f *ProjectEditForm) NextField() {
	f.focusIndex((f.Focus + 1) % ProjectEditFieldCount)
}

// PrevField moves focus to the previous field.
func (f *ProjectEditForm) PrevField() {
	f.focusIndex((f.Focus - 1 + ProjectEditFieldCount) % ProjectEditFieldCount)
}

// Update forwards a message to the focused text input.
func (f *ProjectEditForm) Update(msg tea.Msg) tea.Cmd {
	var cmd tea.Cmd
	f.Inputs[f.Focus], cmd = f.Inputs[f.Focus].Update(msg)
	if f.Focus == FieldToken && f.Inputs[FieldToken].Value() != "" {
		f.tokenChanged = true
	}
	return cmd
}

// Meta builds the Meta to persist. Empty token keeps the previous token.
func (f ProjectEditForm) Meta(previous project.Meta) project.Meta {
	baseURL := strings.TrimSpace(f.Inputs[FieldRemoteURL].Value())
	token := strings.TrimSpace(f.Inputs[FieldToken].Value())
	key := strings.TrimSpace(f.Inputs[FieldProjectKey].Value())

	if baseURL == "" && token == "" && key == "" {
		return project.Meta{YouTrack: nil}
	}

	yt := &project.YouTrack{
		BaseURL:    baseURL,
		ProjectKey: key,
		Token:      token,
	}
	if token == "" && previous.YouTrack != nil {
		yt.Token = previous.YouTrack.Token
	}
	if previous.YouTrack != nil && previous.YouTrack.Query != "" {
		yt.Query = previous.YouTrack.Query
	}
	return project.Meta{YouTrack: yt}
}

// Validate ensures partial YouTrack configs are rejected.
func (f ProjectEditForm) Validate(previous project.Meta) error {
	meta := f.Meta(previous)
	if meta.YouTrack == nil {
		return nil
	}
	yt := meta.YouTrack
	any := yt.BaseURL != "" || yt.Token != "" || yt.ProjectKey != ""
	if any && !yt.Configured() {
		missing := []string{}
		if yt.BaseURL == "" {
			missing = append(missing, "remote URL")
		}
		if yt.Token == "" {
			missing = append(missing, "token")
		}
		if yt.ProjectKey == "" {
			missing = append(missing, "project key")
		}
		return fmt.Errorf("incomplete YouTrack config: missing %s", strings.Join(missing, ", "))
	}
	return nil
}

// View renders the form.
func (f ProjectEditForm) View() string {
	labels := []string{"Remote URL", "Token", "Project key"}
	var b strings.Builder
	b.WriteString(f.Styles.Title.Render(fmt.Sprintf("Edit project %s", f.ProjectID)))
	b.WriteString("\n")
	b.WriteString(f.Styles.Hint.Render("YouTrack sync settings · tab/↑↓ fields · enter save · esc cancel"))
	b.WriteString("\n\n")
	for i, label := range labels {
		b.WriteString(f.Styles.Label.Render(label + ":"))
		b.WriteString("\n")
		b.WriteString(f.Inputs[i].View())
		b.WriteString("\n\n")
	}
	if f.hadToken && !f.tokenChanged {
		b.WriteString(f.Styles.Hint.Render("Token is set; leave blank to keep."))
		b.WriteString("\n")
	}
	return b.String()
}