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

import (
	"fmt"
	"path/filepath"
	"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 }

// Core tea.Model update loop
func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmds []tea.Cmd

	// 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 create:
			m.widget = T
			cmds = append(cmds, T.render, T.init())
		default:
			m.widget = T
			cmds = append(cmds, T.render)
		}
	case loadPath:
		m.Path = string(msg)
		return m, m.load
	case string:
		m.content = msg
	}

	// finally, pass msg to widget
	var cmd tea.Cmd
	switch w := m.widget.(type) {
	case create:
		m.widget, cmd = w.update(msg)
		cmds = append(cmds, cmd, w.render)
	case Issue:
		m.widget, cmd = w.update(msg)
		cmds = append(cmds, cmd)
	case IssueCollection:
		m.widget, cmd = w.update(msg)
		cmds = append(cmds, cmd)
	}

	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..."
	}
	output = output + m.content
	output = output + lipgloss.NewStyle().Faint(true).Margin(1).Render(m.widget.keyhelp())
	return output
}

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

// interface definition for widgets
type widget interface {
	update(tea.Msg) (widget, tea.Cmd) // implements widget specific update life cycles
	render() tea.Msg                  // renders content
	keyhelp() string                  // renders key usage
}

// -------- create widget definitions -----------------------------------------
// ----------------------------------------------------------------------------
// TODO(create widget) handle reset on esc
// TODO(create widget) implement description field in create.create

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

// struct definition for create widget
type create struct {
	inputFields []inputField
	Path        string
	selected    int
	err         error // not implemented
}

// constructor for create widget
func initialCreateWidget(path string, placeholder string) create {
	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)})
		}

		switch t {
		case "title":
			parsed := parsePathToHuman(path)

			if parsed == "." {
				parsed = ""
			}

			inputs[i].input.SetValue(parsed)
		case "status":
			inputs[i].input.SetValue("open")
		}
	}

	return create{
		inputFields: inputs,
		Path:        path,
		selected:    0,
		err:         nil,
	}
}

// init cmd for create widget
func (c create) init() tea.Cmd { return textinput.Blink }

type ( // Type definitions for use in tea.Msg life cycle for create widget.
	createResult Issue    // type wrapper for create.create() result
	writeResult  any      // type wrapper for create.write() result
	editorResult struct { // type wrapper for create.editor() result
		err   error // any error returned by InvokeEditor
		issue Issue // the data in the template file
	}
)

// update cmd for create widget
func (c create) update(msg tea.Msg) (widget, tea.Cmd) {
	var cmds []tea.Cmd
	var cmd tea.Cmd

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

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

	switch msg := msg.(type) { // keybinding handler
	case tea.KeyMsg:
		switch msg.String() {
		case "tab":
			incrementSelected()
		case "shift+tab":
			decrementSelected()
		case "enter":
			if c.selected == len(c.inputFields) { // confirm create
				c.selected++
			} else if c.selected == len(c.inputFields)+1 { // confirmed
				cmds = append(cmds, c.create)
			} else {
				incrementSelected()
			}
		case "esc": // cancel
			cmds = append(cmds, tea.Quit)
		}
	case createResult:
		cmds = append(cmds, c.editDescription(Issue(msg)))
	case editorResult:
		if msg.err != nil {
			c.err = msg.err
		} else {
			cmds = append(cmds, c.write(msg.issue))
		}
	case writeResult:
		switch value := msg.(type) {
		case bool:
			if !value {
			} else {
				cmds = append(cmds, tea.Quit)
			}
		case error:
			c.err = value
		}
	}

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

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

// A tea.Cmd to translate create.inputs to a new Issue object
func (c create) create() tea.Msg {
	data := make(map[string]string)
	commaSplit := func(t string) []string {
		s := strings.Split(t, ",")
		for i, v := range s {
			s[i] = strings.TrimLeft(v, " \t\n")
			s[i] = strings.TrimRight(s[i], " \t\n")

			s[i] = parseHumanToPath(s[i])
		}
		return s
	}

	for _, field := range c.inputFields {
		data[field.title] = field.input.Value()
	}

	var newIssue = Issue{
		Path:      c.Path,
		Tags:      VariadicField{Path: "/tags"},
		Blockedby: VariadicField{Path: "/blockedby"},
	}

	for key, value := range data {
		switch key {
		case "title":
			newIssue.Title = value
			if parsePathToHuman(newIssue.Path) != value {
				dir, _ := filepath.Split(newIssue.Path)
				newIssue.Path = filepath.Join(dir, value)
			}
		case "status":
			newIssue.Status = Field{Path: "/status", Data: value}
		case "description":
			newIssue.Description = Field{Path: "/description", Data: value}
		case "tags":
			splitTags := commaSplit(value)
			for _, tag := range splitTags {
				newIssue.Tags.Fields = append(newIssue.Tags.Fields, Field{Path: tag})
			}
		case "blockers":
			splitBlockedby := commaSplit(value)
			for _, blocker := range splitBlockedby {
				newIssue.Blockedby.Fields = append(
					newIssue.Blockedby.Fields, Field{Path: blocker},
				)
			}
		}
	}

	return createResult(newIssue)
}

// Wraps a tea.Cmd function, passes an initialized Issue to WriteIssue()
func (c create) write(issue Issue) tea.Cmd {
	return func() tea.Msg {
		result, err := WriteIssue(issue, false)
		if err != nil {
			return writeResult(err)
		}
		return writeResult(result)
	}
}

// Calls InvokeEditor via EditTemplate using DescriptionTemplate, reports output
// and errors
//
// WARNING! THIS METHOD HANGS UNTIL THE USER KILLS THE EDITOR!
func (c create) editDescription(issue Issue) tea.Cmd {
	data, err := EditTemplate(DescriptionTemplate, InvokeEditor)
	var output string
	for _, line := range data {
		output = output + line
	}

	issue.Description = Field{Path: "/description", Data: output}

	return func() tea.Msg {
		return editorResult{issue: issue, err: err}
	}
}

// render cmd for create widget
func (c create) render() tea.Msg {
	if c.err != nil {
		return fmt.Sprintf("failed to create issue... %s", c.err.Error())
	}

	borderStyle := lipgloss.NewStyle().
		BorderStyle(lipgloss.NormalBorder()).
		Margin(1).
		Padding(0, 1)

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

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

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

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

	return output
}

// keyhelp cmd for create widget
func (c create) keyhelp() string {
	var output string
	output = output + "\ntab/shift+tab: down/up\t\tenter: input value\t\tctrl+c: quit"
	return output
}

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

// enforce widget interface compliance
func (i Issue) update(tea.Msg) (widget, tea.Cmd) { return i, nil }

// render cmd for Issue widget
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)
}

// keyhelp cmd for Issue widget
func (i Issue) keyhelp() string {
	var output string
	output = output + "\nj/k: down/up\t\tctrl+c: quit"
	return output
}

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

type ( // Type definitions for use in tea.Msg life cycle for IssueCollection widget.
	loadPath string // thrown when user selects a path to load.
)

// enforce widget interface compliance
func (ic IssueCollection) update(msg tea.Msg) (widget, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "j":
			if ic.selection+1 < len(ic.Collection) {
				ic.selection = ic.selection + 1
			} else {
				ic.selection = 0
			}
			return ic, ic.render
		case "k":
			if ic.selection != 0 {
				ic.selection = ic.selection - 1
			} else {
				ic.selection = len(ic.Collection) - 1
			}
			return ic, ic.render
		case "enter":
			ic.Path = ic.Collection[ic.selection].Path
			return ic, ic.sendLoad
		case "q":
			return ic, tea.Quit
		}
	}

	return ic, nil
}

func (ic IssueCollection) sendLoad() tea.Msg { return loadPath(ic.Path) }

// render cmd for IssueCollection widget
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
}

// keyhelp cmd for IssueCollection widget
func (ic IssueCollection) keyhelp() string {
	var output string
	output = output + "\nj/k: down/up\t\tenter: select\t\tq/ctrl+c: quit"
	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 initialCreateWidget(m.Path, "lorem ipsum")
}