// The package defines an extensible TUI via the bubbletea framework.
//
// TODO enable collection recursing (i.e, embeded collections)
//
// TODO enable scroll/viewport logic on issues!!!
//
// While the package remains in v0.0.X releases, this TUI may be undocumented.
package issues

import (
	"fmt"
	"strings"

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

// [lipgloss] style definitions, stores the currently displayed "widget"
var (
	titleStyle = lipgloss.NewStyle().
			Bold(true).
			Underline(true)

	statusStyle = lipgloss.NewStyle().
			Faint(true).
			Italic(true)

	variadicTitleStyle = lipgloss.NewStyle().
				Align(lipgloss.Left).
				Italic(true)

	variadicDataStyle = lipgloss.NewStyle().
				Width(40).
				BorderStyle(lipgloss.ASCIIBorder())

	borderStyle = lipgloss.NewStyle().
			Padding(1, 2).
			Margin(1).
			BorderStyle(lipgloss.NormalBorder())

	indexStyle = lipgloss.NewStyle().
			Italic(true)

	pointerStyle = lipgloss.NewStyle().
			Faint(true)

	collectionStyleLeft = lipgloss.NewStyle().
				Align(lipgloss.Left)
)

// interface for renderable structs
type widget interface {
	view() tea.Msg
}

// The main bubbletea Model
type Model struct {
	widget  widget
	content string
	Path    string
	// viewport viewport.Model
}

// The bubbletea init function
func (m Model) Init() tea.Cmd { return m.load }

// Handles quit logic and viewport scroll and size updates
func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "q":
			return m, tea.Quit
		case "j":
			if collection, ok := m.widget.(IssueCollection); ok {
				if collection.selection+1 < len(collection.Collection) {
					collection.selection = collection.selection + 1
				} else {
					collection.selection = 0
				}
				m.widget = collection
				return m, collection.view
			}
			return m, nil
		case "k":
			// do something only if widget is collection
			if collection, ok := m.widget.(IssueCollection); ok {
				if collection.selection != 0 {
					collection.selection = collection.selection - 1
				} else {
					collection.selection = len(collection.Collection) - 1
				}
				m.widget = collection
				return m, collection.view
			}
			return m, nil
		case "enter":
			if _, ok := m.widget.(IssueCollection); ok {
				m.Path = m.widget.(IssueCollection).Collection[m.widget.(IssueCollection).selection].Path
				return m, m.load
			}
			return m, nil
		}
	case widget:
		switch T := msg.(type) {
		case Issue:
			m.widget = T
			return m, T.view
		case IssueCollection:
			m.widget = T
			return m, T.view
		}
	case string:
		m.content = msg
		return m, nil
	}

	return m, nil
}

// Handles top level view functionality
func (m Model) View() string {
	var output string
	if len(m.content) == 0 {
		return "loading..."
	} else {
		output = output + m.content
	}
	output = output + "\nj/k: down/up\tenter: select\tq: quit"
	return output
}

type issueCreate struct {
	focusedField int
	inputs       []textinput.Model
	issue        Issue
}

func (c issueCreate) init(i Issue) issueCreate {
	c.issue = i
	title := textinput.Model{Placeholder: "title", CharLimit: 64, Width: 45}
	status := textinput.Model{Placeholder: "status", CharLimit: 64, Width: 45}
	tags := textinput.Model{Placeholder: "tags", CharLimit: 64, Width: 45}
	blockers := textinput.Model{Placeholder: "blockers", CharLimit: 64, Width: 45}
	c.inputs = append(c.inputs, title, status, tags, blockers)
	return c
}

func (c issueCreate) update(msg tea.Msg) (issueCreate, tea.Cmd) {
	switch T := msg.(type) {
	case issueCreate:
		c.issue = T.issue
		c.focusedField = T.focusedField
		c.inputs = T.inputs

		return c, nil
	case tea.KeyMsg:
		switch T.String() {
		case "tab":
			if c.focusedField < len(c.inputs)-1 {
				c.focusedField++
			} else {
				c.focusedField = 0
			}
			return c, nil
		default:
			inputModel, inputCmd := c.inputs[c.focusedField].Update(msg)
			c.inputs[c.focusedField] = inputModel
			return c, inputCmd
		}
	}

	return c, nil
}

func (c issueCreate) view() tea.Msg { return "testing" }

// Handles load logic
func (m Model) load() tea.Msg {
	if IsIssue(m.Path) {
		issue, err := Issue{}.NewFromPath(m.Path)

		if err != nil {
			return nil
		}

		return issue
	}

	if IsIssueCollection(m.Path) {
		collection, err := IssueCollection{}.NewFromPath(m.Path)

		if err != nil {
			return nil
		}

		return collection
	}

	return issueCreate{issue: Issue{Path: m.Path}}
}

// Handles all view logic for Issue structs
func (i Issue) view() tea.Msg {
	var output string
	// title
	output = output + titleStyle.Render(i.Title)

	// status
	output = output + fmt.Sprintf("\n%s", statusStyle.Render(i.Status.Data))

	// variadics
	var tags string
	for _, field := range i.Tags.Fields {
		tags = tags + field.Path + ", "
	}
	tags = strings.TrimRight(tags, ", ")

	var blockedby string
	for _, field := range i.Blockedby.Fields {
		blockedby = blockedby + field.Path + ", "
	}
	blockedby = strings.TrimRight(blockedby, ", ")

	if len(i.Tags.Fields) > 0 {
		output = output + variadicTitleStyle.Render("\n\nTags:")
		output = output + fmt.Sprintf("\n%s", variadicDataStyle.Render(tags))
	}

	if len(i.Blockedby.Fields) > 0 {
		output = output + variadicTitleStyle.Render("\n\nBlockedby:")
		output = output + fmt.Sprintf("\n%s", variadicDataStyle.Render(blockedby))
	}

	// description
	output = output + titleStyle.Render("\n\nDescription:\n")
	output = output + fmt.Sprintf("\n%s", i.Description.Data)

	return borderStyle.Render(output)
}

// Handles all view logic for IssueCollection structs.
func (ic IssueCollection) view() tea.Msg {
	var output string
	var left string
	output = output + "Issues in " + ic.Path + "...\n\n"
	for i, issue := range ic.Collection {
		// pointer render
		if i == ic.selection {
			left = left + pointerStyle.Render("-> ")
		} else {
			left = left + pointerStyle.Render("   ")
		}
		// index render
		left = left + "[" + indexStyle.Render(fmt.Sprintf("%d", i+1)) + "]: "

		// title render
		left = left + fmt.Sprintf("%s\n", titleStyle.Render(issue.Title))
	}

	output = output + collectionStyleLeft.Render(left)
	return output
}