package ui

import (
	"database/sql"
	"fmt"
	"io"
	"sort"
	"strings"

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

	"skyrama-tui/internal/model"
	"skyrama-tui/internal/service"
	"skyrama-tui/internal/style"
)

// ─── Messages ─────────────────────────────────────────────────────────────────

type BuildingsLoadedMsg struct {
	Owned                        []model.AirportBuilding
	Catalogue                    []model.Building
	StorageCount, OperationCount int
	StorageCap, OperationCap     uint32
}
type BuildingsErrMsg struct{ Err error }
type BuildingConstructedMsg struct{ Name string }
type BuildingDemolishedMsg struct{ Fee int64 }
type CapUpgradedMsg struct{ Type string }

// ─── List items ───────────────────────────────────────────────────────────────

type ownedBuildingItem struct{ b model.AirportBuilding }

func (o ownedBuildingItem) Title() string {
	return buildingEmoji(o.b.BuildingType) + " " + o.b.Name
}
func (o ownedBuildingItem) Description() string {
	parts := []string{
		style.Muted.Render("type:" + o.b.BuildingType),
		style.Muted.Render(fmt.Sprintf("lv.%d", o.b.Level)),
	}
	if o.b.Capacity.Valid {
		parts = append(parts, style.FuelChip.Render(fmt.Sprintf("cap:%d", o.b.Capacity.Int32)))
	}
	if o.b.OperationType.Valid {
		parts = append(parts, style.PassengerChip.Render("op:"+o.b.OperationType.String))
	}
	if o.b.OperationSize.Valid {
		parts = append(parts, style.Muted.Render("size:"+o.b.OperationSize.String))
	}
	return strings.Join(parts, "  ")
}
func (o ownedBuildingItem) FilterValue() string { return o.b.Name }

type catalogueItem struct{ b model.Building }

func (c catalogueItem) Title() string {
	return buildingEmoji(c.b.BuildingType) + " " + c.b.Name +
		style.CashChip.Render(fmt.Sprintf("  ($%d)", c.b.ConstructionCostCash))
}
func (c catalogueItem) Description() string {
	parts := []string{
		"type:" + c.b.BuildingType,
		fmt.Sprintf("min.lv%d", c.b.MinLevel),
	}
	if c.b.Capacity.Valid {
		parts = append(parts, fmt.Sprintf("cap:%d", c.b.Capacity.Int32))
	}
	if c.b.OperationType.Valid {
		parts = append(parts, "op:"+c.b.OperationType.String)
	}
	if c.b.OperationSize.Valid {
		parts = append(parts, "size:"+c.b.OperationSize.String)
	}
	if c.b.PassiveRate.Valid && c.b.PassiveType.Valid {
		parts = append(parts, fmt.Sprintf("+%d/s %s", c.b.PassiveRate.Int32, c.b.PassiveType.String))
	}
	return style.Muted.Render(strings.Join(parts, "  "))
}
func (c catalogueItem) FilterValue() string { return c.b.Name }

// ─── BuildingsModel ───────────────────────────────────────────────────────────

type BuildingsModel struct {
	client                       *service.GameService
	airportID                    uint32
	ownedList                    list.Model
	shopList                     list.Model
	subTab                       int // 0 = owned, 1 = build catalogue
	owned                        []model.AirportBuilding
	catalogue                    []model.Building
	storageCount, operationCount int
	storageCap, operationCap     uint32
	statusMsg                    string
	demolishArmed                bool // a demolish confirmation is pending (next y confirms)
	focused                      bool
	width                        int
	height                       int
}

func NewBuildingsModel(client *service.GameService, airportID uint32) BuildingsModel {
	mkList := func() list.Model {
		base := list.NewDefaultDelegate()
		base.Styles.SelectedTitle = base.Styles.SelectedTitle.
			Foreground(style.ColorSky).
			BorderForeground(style.ColorSky)
		base.Styles.SelectedDesc = base.Styles.SelectedDesc.
			Foreground(style.ColorPassenger).
			BorderForeground(style.ColorSky)
		d := buildingDelegate{DefaultDelegate: base}
		l := list.New(nil, d, 0, 0)
		l.Title = ""
		l.SetShowTitle(false)
		l.SetShowHelp(false)
		l.SetShowStatusBar(false)
		l.SetFilteringEnabled(true)
		return l
	}
	return BuildingsModel{
		client:    client,
		airportID: airportID,
		ownedList: mkList(),
		shopList:  mkList(),
	}
}

func (m BuildingsModel) Init() tea.Cmd { return m.load() }

func (m BuildingsModel) Update(msg tea.Msg) (BuildingsModel, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.width = msg.Width
		m.height = msg.Height
		h := m.height - 13
		if h < 4 {
			h = 4
		}
		m.ownedList.SetSize(m.width-4, h)
		m.shopList.SetSize(m.width-4, h)

	case BuildingsLoadedMsg:
		m.owned = msg.Owned
		m.catalogue = msg.Catalogue
		m.storageCount, m.operationCount = msg.StorageCount, msg.OperationCount
		m.storageCap, m.operationCap = msg.StorageCap, msg.OperationCap
		ownedItems := ownedToItems(msg.Owned)
		shopItems := catalogueToItems(msg.Catalogue)
		m.ownedList.SetItems(ownedItems)
		m.shopList.SetItems(shopItems)
		m.ownedList.Select(firstSelectable(ownedItems))
		m.shopList.Select(firstSelectable(shopItems))

	case BuildingConstructedMsg:
		m.statusMsg = style.Success.String() + "Built: " + msg.Name
		return m, m.load()

	case BuildingDemolishedMsg:
		m.statusMsg = style.Success.String() + fmt.Sprintf("Demolished (−$%d)", msg.Fee)
		return m, m.load()

	case CapUpgradedMsg:
		m.statusMsg = style.Success.String() + msg.Type + " capacity increased!"
		return m, m.load()

	case BuildingsErrMsg:
		m.statusMsg = style.Error.String() + msg.Err.Error()

	case tea.KeyMsg:
		if !m.focused {
			break
		}
		// A demolish confirmation is pending: y confirms, anything else cancels.
		if m.demolishArmed {
			m.demolishArmed = false
			if msg.String() == "y" || msg.String() == "Y" {
				return m, m.demolishSelected()
			}
			m.statusMsg = style.Muted.Render("Demolition cancelled.")
			return m, nil
		}
		switch msg.String() {
		case "h", "left":
			m.subTab = 0
		case "l", "right":
			m.subTab = 1
		case "r":
			m.statusMsg = ""
			return m, m.load()
		case "d", "D":
			if m.subTab == 0 {
				item, ok := m.ownedList.SelectedItem().(ownedBuildingItem)
				if !ok {
					break
				}
				m.demolishArmed = true
				m.statusMsg = style.Warning.String() +
					fmt.Sprintf("Demolish %s for $%d (no refund)? (y/n)",
						item.b.Name, demolishFee(item.b))
				return m, nil
			}
		case "c", "C":
			if m.subTab == 1 {
				item, ok := m.shopList.SelectedItem().(catalogueItem)
				if !ok {
					break
				}
				return m, m.buyCapUpgrade(item.b.BuildingType)
			}
		case "enter", " ":
			if m.subTab == 1 {
				return m, m.buildSelected()
			}
		}
	}

	var cmd tea.Cmd
	if m.subTab == 0 {
		m.ownedList, cmd = m.ownedList.Update(msg)
	} else {
		m.shopList, cmd = m.shopList.Update(msg)
	}
	// Keep the cursor off non-selectable section headers.
	if key, ok := msg.(tea.KeyMsg); ok {
		if m.subTab == 0 {
			skipHeaders(&m.ownedList, key.String())
		} else {
			skipHeaders(&m.shopList, key.String())
		}
	}
	return m, cmd
}

func (m BuildingsModel) View() string {
	// Sub-tab headers
	ownedTab := style.Muted.Render("  Owned  ")
	buildTab := style.Muted.Render("  Build  ")
	if m.subTab == 0 {
		ownedTab = style.CashChip.Render(" ▶ Owned ")
	} else {
		buildTab = style.CashChip.Render(" ▶ Build ")
	}
	tabs := lipgloss.JoinHorizontal(lipgloss.Top,
		ownedTab,
		style.Muted.Render(" │ "),
		buildTab,
	)

	statusLine := ""
	if m.statusMsg != "" {
		statusLine = "\n" + m.statusMsg + "\n"
	}

	var help string
	if m.subTab == 0 {
		help = style.HelpKey.Render("h/l") + style.HelpDesc.Render(" switch  ") +
			style.HelpKey.Render("d") + style.HelpDesc.Render(" demolish  ") +
			style.HelpKey.Render("r") + style.HelpDesc.Render(" refresh  ") +
			style.HelpKey.Render("/") + style.HelpDesc.Render(" filter")
	} else {
		help = style.HelpKey.Render("h/l") + style.HelpDesc.Render(" switch  ") +
			style.HelpKey.Render("enter") + style.HelpDesc.Render(" build  ") +
			style.HelpKey.Render("c") + style.HelpDesc.Render(" expand cap  ") +
			style.HelpKey.Render("r") + style.HelpDesc.Render(" refresh")
	}

	capLine := style.Muted.Render(fmt.Sprintf("Caps:  📦 storage %d/%d   🛬 operation %d/%d",
		m.storageCount, m.storageCap, m.operationCount, m.operationCap))

	var content string
	if m.subTab == 0 {
		if len(m.owned) == 0 {
			content = style.Muted.Render("No buildings yet. Switch to Build tab (l / →) to construct some.")
		} else {
			content = m.ownedList.View()
		}
	} else {
		if len(m.catalogue) == 0 {
			content = style.Muted.Render("No buildings available in the catalogue.")
		} else {
			content = m.shopList.View()
		}
	}

	return lipgloss.JoinVertical(lipgloss.Left,
		style.PanelHeader.Render("🏗  Buildings"),
		tabs,
		capLine,
		statusLine,
		content,
		"",
		style.Muted.Render(help),
	)
}

// ─── Exported for parent AppModel ─────────────────────────────────────────────

// Load is the exported version for use by parent AppModel.
func (m BuildingsModel) Load() tea.Cmd { return m.load() }

func (m BuildingsModel) load() tea.Cmd {
	client := m.client
	airportID := m.airportID
	return func() tea.Msg {
		owned, err := client.GetAirportBuildings(airportID)
		if err != nil {
			return BuildingsErrMsg{Err: err}
		}
		cat, err := client.GetAllBuildings()
		if err != nil {
			return BuildingsErrMsg{Err: err}
		}
		storageCount, operationCount, err := client.BuildingCounts(airportID)
		if err != nil {
			return BuildingsErrMsg{Err: err}
		}
		storageCap, operationCap, err := client.GetCaps(airportID)
		if err != nil {
			return BuildingsErrMsg{Err: err}
		}
		return BuildingsLoadedMsg{
			Owned: owned, Catalogue: cat,
			StorageCount: storageCount, OperationCount: operationCount,
			StorageCap: storageCap, OperationCap: operationCap,
		}
	}
}

func (m BuildingsModel) buildSelected() tea.Cmd {
	item, ok := m.shopList.SelectedItem().(catalogueItem)
	if !ok {
		return nil
	}
	client := m.client
	airportID := m.airportID
	b := item.b
	return func() tea.Msg {
		if err := client.ConstructBuilding(airportID, b.ID); err != nil {
			return BuildingsErrMsg{Err: err}
		}
		return BuildingConstructedMsg{Name: b.Name}
	}
}

func (m BuildingsModel) demolishSelected() tea.Cmd {
	item, ok := m.ownedList.SelectedItem().(ownedBuildingItem)
	if !ok {
		return nil
	}
	client := m.client
	airportID := m.airportID
	id := item.b.ID
	return func() tea.Msg {
		fee, err := client.DemolishBuilding(airportID, id)
		if err != nil {
			return BuildingsErrMsg{Err: err}
		}
		return BuildingDemolishedMsg{Fee: fee}
	}
}

func (m BuildingsModel) buyCapUpgrade(buildingType string) tea.Cmd {
	client := m.client
	airportID := m.airportID
	return func() tea.Msg {
		if err := client.BuyCapUpgrade(airportID, buildingType); err != nil {
			return BuildingsErrMsg{Err: err}
		}
		return CapUpgradedMsg{Type: buildingType}
	}
}

// demolishFee previews the cost to demolish: a quarter of construction cost.
// (Authoritative value is computed by DemolishBuilding.)
func demolishFee(b model.AirportBuilding) int64 {
	return int64(b.ConstructionCostCash) / 4
}

// ─── Grouping ─────────────────────────────────────────────────────────────────

// buildingHeader is a non-actionable section / sub-section label inserted between
// grouped building rows. Empty FilterValue so it disappears during text filtering.
type buildingHeader struct {
	label string
	top   bool // true = building-type header, false = storage/operation subtype
}

func (h buildingHeader) Title() string       { return h.label }
func (h buildingHeader) Description() string { return "" }
func (h buildingHeader) FilterValue() string { return "" }

// buildingDelegate renders header rows as plain section labels and delegates
// every other row to the default delegate.
type buildingDelegate struct{ list.DefaultDelegate }

func (d buildingDelegate) Render(w io.Writer, m list.Model, index int, it list.Item) {
	if h, ok := it.(buildingHeader); ok {
		if h.top {
			fmt.Fprint(w, "  "+style.PanelHeader.Render(h.label))
		} else {
			fmt.Fprint(w, "  "+style.Muted.Render(h.label))
		}
		return
	}
	d.DefaultDelegate.Render(w, m, index, it)
}

// typeRank orders building-type sections.
func typeRank(t string) int {
	switch t {
	case "storage":
		return 0
	case "operation":
		return 1
	case "passive":
		return 2
	case "support":
		return 3
	case "shop":
		return 4
	case "production":
		return 5
	default:
		return 6
	}
}

// groupable is one row plus the keys used to sort + section it.
type groupable struct {
	item    list.Item
	typ     string
	subtype string
	name    string
}

// buildGrouped sorts rows by type → subtype → name and inserts section headers
// (a type header for every type; a subtype header within storage/operation).
func buildGrouped(rows []groupable) []list.Item {
	sort.SliceStable(rows, func(i, j int) bool {
		if ri, rj := typeRank(rows[i].typ), typeRank(rows[j].typ); ri != rj {
			return ri < rj
		}
		if rows[i].subtype != rows[j].subtype {
			return rows[i].subtype < rows[j].subtype
		}
		return rows[i].name < rows[j].name
	})

	var out []list.Item
	curType, curSub := "", ""
	first := true
	for _, r := range rows {
		if first || r.typ != curType {
			out = append(out, buildingHeader{label: buildingEmoji(r.typ) + " " + strings.ToUpper(r.typ), top: true})
			curType, curSub, first = r.typ, "", false
		}
		if (r.typ == "storage" || r.typ == "operation") && r.subtype != "" && r.subtype != curSub {
			out = append(out, buildingHeader{label: "   • " + r.subtype})
			curSub = r.subtype
		}
		out = append(out, r.item)
	}
	return out
}

// firstSelectable returns the index of the first non-header item (or 0).
func firstSelectable(items []list.Item) int {
	for i, it := range items {
		if _, isHeader := it.(buildingHeader); !isHeader {
			return i
		}
	}
	return 0
}

// skipHeaders nudges the list cursor off a header row in the travel direction,
// so selection always lands on a real building.
func skipHeaders(l *list.Model, key string) {
	if _, isHeader := l.SelectedItem().(buildingHeader); !isHeader {
		return
	}
	up := key == "up" || key == "k"
	for range l.Items() {
		if _, isHeader := l.SelectedItem().(buildingHeader); !isHeader {
			return
		}
		if up {
			l.CursorUp()
		} else {
			l.CursorDown()
		}
	}
}

// ─── List converters ──────────────────────────────────────────────────────────

func ownedToItems(owned []model.AirportBuilding) []list.Item {
	rows := make([]groupable, len(owned))
	for i, b := range owned {
		rows[i] = groupable{
			item:    ownedBuildingItem{b: b},
			typ:     b.BuildingType,
			subtype: buildingSubtype(b.BuildingType, b.StorageType, b.OperationType),
			name:    b.Name,
		}
	}
	return buildGrouped(rows)
}

func catalogueToItems(cat []model.Building) []list.Item {
	rows := make([]groupable, len(cat))
	for i, b := range cat {
		rows[i] = groupable{
			item:    catalogueItem{b: b},
			typ:     b.BuildingType,
			subtype: buildingSubtype(b.BuildingType, b.StorageType, b.OperationType),
			name:    b.Name,
		}
	}
	return buildGrouped(rows)
}

// buildingSubtype is the storage_type (storage) or operation_type (operation),
// used to sub-group within those sections.
func buildingSubtype(buildingType string, storageType, operationType sql.NullString) string {
	switch buildingType {
	case "storage":
		if storageType.Valid {
			return storageType.String
		}
	case "operation":
		if operationType.Valid {
			return operationType.String
		}
	}
	return ""
}

// ─── Helpers ──────────────────────────────────────────────────────────────────

func buildingEmoji(buildingType string) string {
	switch buildingType {
	case "storage":
		return "📦"
	case "operation":
		return "🛬"
	case "passive":
		return "⚡"
	case "support":
		return "🔧"
	case "shop":
		return "🏪"
	case "production":
		return "🏭"
	default:
		return "🏢"
	}
}