package tui

import (
	"fmt"
	"sort"
	"strings"

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

	"proxyctl/internal/app"
	"proxyctl/internal/profile"
)

// profilePickerState is the dashboard's routine Active Profile switching
// component. Bubbles owns text editing and viewport clipping; this type only
// supplies the product ordering and identity-based selection rules.
type profilePickerState struct {
	open         bool
	search       textinput.Model
	selectedName string
}

func newProfilePickerState() profilePickerState {
	search := textinput.New()
	search.Prompt = "Search: "
	search.Placeholder = "type to filter by name"
	search.CharLimit = 256
	return profilePickerState{search: search}
}

func (p *profilePickerState) show(snapshot app.Snapshot) tea.Cmd {
	p.open = true
	p.search.SetValue("")
	p.search.CursorEnd()
	p.selectedName = ""
	p.retainSelection(snapshot)
	return p.search.Focus()
}

func (p *profilePickerState) close() {
	p.open = false
	p.search.Blur()
}

func (p *profilePickerState) update(key tea.KeyMsg, snapshot app.Snapshot) tea.Cmd {
	switch key.String() {
	case "up", "ctrl+p":
		p.move(snapshot, -1)
		return nil
	case "down", "ctrl+n":
		p.move(snapshot, 1)
		return nil
	case "pgup":
		p.move(snapshot, -8)
		return nil
	case "pgdown":
		p.move(snapshot, 8)
		return nil
	}
	previous := p.search.Value()
	var command tea.Cmd
	p.search, command = p.search.Update(key)
	if p.search.Value() != previous {
		p.retainSelection(snapshot)
	}
	return command
}

func (p *profilePickerState) move(snapshot app.Snapshot, delta int) {
	items := p.filtered(snapshot)
	if len(items) == 0 {
		p.selectedName = ""
		return
	}
	index := profileIndex(items, p.selectedName)
	if index < 0 {
		index = 0
	}
	index = max(0, min(len(items)-1, index+delta))
	p.selectedName = items[index].Name
}

func (p *profilePickerState) retainSelection(snapshot app.Snapshot) {
	items := p.filtered(snapshot)
	if profileIndex(items, p.selectedName) >= 0 {
		return
	}
	p.selectedName = ""
	if len(items) > 0 {
		p.selectedName = items[0].Name
	}
}

func (p profilePickerState) selected(snapshot app.Snapshot) (profile.Profile, bool) {
	items := p.filtered(snapshot)
	index := profileIndex(items, p.selectedName)
	if index < 0 {
		return profile.Profile{}, false
	}
	return items[index], true
}

func (p profilePickerState) filtered(snapshot app.Snapshot) []profile.Profile {
	ordered := orderedProfiles(snapshot)
	query := strings.ToLower(strings.TrimSpace(p.search.Value()))
	if query == "" {
		return ordered
	}
	filtered := make([]profile.Profile, 0, len(ordered))
	for _, item := range ordered {
		if strings.Contains(strings.ToLower(item.Name), query) {
			filtered = append(filtered, item)
		}
	}
	return filtered
}

func orderedProfiles(snapshot app.Snapshot) []profile.Profile {
	items := append([]profile.Profile(nil), snapshot.Profiles...)
	sort.SliceStable(items, func(i, j int) bool {
		left, right := strings.ToLower(items[i].Name), strings.ToLower(items[j].Name)
		if left == right {
			return items[i].Name < items[j].Name
		}
		return left < right
	})
	activeIndex := profileIndex(items, snapshot.ActiveProfile)
	if activeIndex <= 0 {
		return items
	}
	active := items[activeIndex]
	copy(items[1:activeIndex+1], items[:activeIndex])
	items[0] = active
	return items
}

func profileIndex(items []profile.Profile, name string) int {
	for i := range items {
		if items[i].Name == name {
			return i
		}
	}
	return -1
}

func (p profilePickerState) view(snapshot app.Snapshot, width, height int) string {
	search := p.search
	search.Width = max(12, width-len(search.Prompt)-4)

	items := p.filtered(snapshot)
	lines := make([]string, 0, len(items))
	selectedIndex := profileIndex(items, p.selectedName)
	for _, item := range items {
		cursor := "  "
		if item.Name == p.selectedName {
			cursor = "> "
		}
		active := ""
		if item.Name == snapshot.ActiveProfile {
			active = "★ "
		}
		line := cursor + active + item.Name
		if item.Name == snapshot.ActiveProfile {
			line += " — Active Profile"
		}
		lines = append(lines, line)
	}
	if len(lines) == 0 {
		selectedIndex = 0
		if len(snapshot.Profiles) == 0 {
			lines = append(lines, "No Proxy Profiles are available.", "Press Escape, then open Profile management to create one.")
		} else {
			lines = append(lines, fmt.Sprintf("No Proxy Profiles match %q.", p.search.Value()), "Edit the search or press Escape to cancel.")
		}
	}

	listHeight := max(2, height-5)
	list := viewport.New(max(1, width), listHeight)
	list.SetContent(strings.Join(lines, "\n"))
	if selectedIndex >= listHeight {
		list.SetYOffset(selectedIndex - listHeight + 1)
	}
	return "Switch Active Profile\n" + search.View() + "\n" + paneRule(width) + "\n" + list.View()
}