// 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"
)

// Type and Style definitions -------------------------------------------------
// ----------------------------------------------------------------------------

// [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)
)

// MAIN MODEL DEFINITIONS -----------------------------------------------------
// ----------------------------------------------------------------------------

// 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) {
	// widget specifc keyhandling
	var cmds []tea.Cmd
	switch m.widget.(type) {
	case IssueCollection:
		if msg, ok := msg.(tea.KeyMsg); ok {
			switch msg.String() {
			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.render
				}
			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.render
				}
			case "enter":
				if _, ok := m.widget.(IssueCollection); ok {
					m.Path = m.widget.(IssueCollection).Collection[m.widget.(IssueCollection).selection].Path
					return m, m.load
				}
			case "q":
				cmds = append(cmds, tea.Quit)
			}
		}
	}

	// general message handling
	switch msg := msg.(type) {
	case tea.KeyMsg: // keymsg capture that is always present
		switch msg.String() {
		case "ctrl+c":
			cmds = append(cmds, tea.Quit)
		}
	case widget: // widget is initialized from m.load()
		switch T := msg.(type) {
		case createIssue:
			m.widget = T
			cmds = append(cmds, T.render, T.init())
		default:
			m.widget = T
			cmds = append(cmds, T.render)
		}
	case string:
		m.content = msg
	}

	// finally, handle input updates if any
	if w, ok := m.widget.(createIssue); ok {
		var cmd tea.Cmd
		m.widget, cmd = w.update(msg)
		cmds = append(cmds, cmd, w.render)
	}

	return m, tea.Batch(cmds...)
}

// 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
}

// WIDGET DEFINITIONS ---------------------------------------------------------
// ----------------------------------------------------------------------------

// interface definition for widgets
type widget interface {
	render() tea.Msg
}

// -------- creatIssue definitions --------------------------------------------
// ----------------------------------------------------------------------------

// data struct for createIssue
type inputField struct {
	input textinput.Model
	title string
}

// widget for creating an issue
type createIssue struct {
	inputFields []inputField
	Path        string
	selected    int
	Err         error // behaviour undefined
}

func initialInputModel(path string, placeholder string) createIssue {
	spawnInput := func(f bool) textinput.Model {
		ti := textinput.New()
		ti.Placeholder = placeholder
		if f {
			ti.Focus()
		}
		ti.CharLimit = 80
		ti.Width = 30
		return ti
	}

	var inputs []inputField
	for i, t := range [4]string{"title", "status", "tags", "blockers"} {
		if i == 0 {
			inputs = append(inputs, inputField{title: t, input: spawnInput(true)})
		} else {
			inputs = append(inputs, inputField{title: t, input: spawnInput(false)})
		}
	}

	return createIssue{
		inputFields: inputs,
		Path:        path,
		selected:    0,
		Err:         nil,
	}
}

func (ci createIssue) init() tea.Cmd {
	return textinput.Blink
}

func (ci createIssue) update(msg tea.Msg) (createIssue, tea.Cmd) {
	var cmds []tea.Cmd
	var cmd tea.Cmd

	// simple anon funcs to increment the selected index
	incrementSelected := func() {
		if ci.selected < len(ci.inputFields) {
			ci.selected++
			for i := 0; i < len(ci.inputFields); i++ {
				if i == ci.selected {
					ci.inputFields[i].input.Focus()
				} else {
					ci.inputFields[i].input.Blur()
				}
			}
		} else {
			ci.selected = 0
			ci.inputFields[ci.selected].input.Focus()
		}
	}

	decrementSelected := func() {
		if ci.selected != 0 {
			ci.selected--
			for i := 0; i < len(ci.inputFields); i++ {
				if i == ci.selected {
					ci.inputFields[i].input.Focus()
				} else {
					ci.inputFields[i].input.Blur()
				}
			}
		} else {
			for i := 0; i < len(ci.inputFields); i++ {
				ci.inputFields[i].input.Blur()
			}
			ci.selected = len(ci.inputFields)
		}
	}

	switch msg := msg.(type) { // keybinding handler
	case tea.KeyMsg:
		switch msg.String() {
		case "tab":
			incrementSelected()
		case "shift+tab":
			decrementSelected()
		case "enter":
			if ci.selected == len(ci.inputFields) { // confirm create
				ci.selected++
			} else if ci.selected == len(ci.inputFields)+1 { // confirmed
				cmds = append(cmds, tea.Quit)
			} else {
				incrementSelected()
			}
		case "esc": // cancel
			cmds = append(cmds, tea.Quit)
		}
	}

	for i, ti := range ci.inputFields {
		ci.inputFields[i].input, cmd = ti.input.Update(msg)
		cmds = append(cmds, cmd)
	}

	cmds = append(cmds, cmd)
	return ci, tea.Batch(cmds...)
}

func (ci createIssue) render() tea.Msg {
	borderStyle := lipgloss.NewStyle().
		BorderStyle(lipgloss.NormalBorder()).
		Margin(1).
		Padding(0, 1)

	ulStyle := lipgloss.NewStyle().Underline(true)

	var output string
	for _, field := range ci.inputFields {
		output = output + fmt.Sprintf(
			"\n%s:%s",
			field.title,
			borderStyle.Render(field.input.View()),
		)
	}

	output = strings.TrimLeft(output, "\n")

	if ci.selected < len(ci.inputFields) {
		output = output + borderStyle.Render("press enter to submit...")
	} else if ci.selected == len(ci.inputFields) {
		output = output + borderStyle.Render(ulStyle.Render("press enter to submit..."))
	} else if ci.selected == len(ci.inputFields)+1 {
		confirmPrompt := fmt.Sprintf(
			"creating issue titled \"%s\"...\n\n%s",
			ulStyle.Render(ci.inputFields[0].input.Value()),
			ulStyle.Render("press enter to confirm..."),
		)
		output = output + borderStyle.Render(confirmPrompt)
	}
	return output
}

// -------- Issue widget definitions ------------------------------------------
// ----------------------------------------------------------------------------

// Handles all render logic for Issue structs
func (i Issue) render() 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)
}

// -------- IssueCollection widget definitions --------------------------------
// ----------------------------------------------------------------------------

// Handles all render logic for IssueCollection structs.
func (ic IssueCollection) render() 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
}

// tea.Cmd definitions --------------------------------------------------------
// ----------------------------------------------------------------------------

// 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 initialInputModel(m.Path, "lorem ipsum")
}