package tui

import (
	"fmt"
	"strings"

	tea "github.com/charmbracelet/bubbletea"

	"github.com/lerko/nib/internal/db"
	"github.com/lerko/nib/internal/display"
)

type absorbModel struct {
	targetID string
	sources  []*db.Entity
	cursor   int
	offset   int
	height   int
}

func newAbsorbModel(targetID string) absorbModel {
	return absorbModel{targetID: targetID}
}

func (a *absorbModel) setSources(entities []*db.Entity) {
	a.sources = nil
	for _, e := range entities {
		if e.ID != a.targetID {
			a.sources = append(a.sources, e)
		}
	}
	a.cursor = 0
	a.offset = 0
}

func (a *absorbModel) setHeight(h int) {
	a.height = h
}

func (a absorbModel) selectedSource() *db.Entity {
	if len(a.sources) == 0 || a.cursor >= len(a.sources) {
		return nil
	}
	return a.sources[a.cursor]
}

func (a absorbModel) update(msg tea.KeyMsg) absorbModel {
	switch msg.String() {
	case "up", "k":
		if a.cursor > 0 {
			a.cursor--
			if a.cursor < a.offset {
				a.offset = a.cursor
			}
		}
	case "down", "j":
		if a.cursor < len(a.sources)-1 {
			a.cursor++
			visible := a.visibleCount()
			if a.cursor >= a.offset+visible {
				a.offset = a.cursor - visible + 1
			}
		}
	}
	return a
}

func (a absorbModel) view(width int) string {
	if len(a.sources) == 0 {
		return statusStyle.Render("no other entities")
	}

	var b strings.Builder
	b.WriteString(titleStyle.Render("absorb into " + display.FormatID(a.targetID)))
	b.WriteString("\n")
	b.WriteString(helpStyle.Render("select source to merge"))
	b.WriteString("\n\n")

	visible := a.visibleCount() - 4
	if visible <= 0 {
		visible = 10
	}
	end := min(a.offset+visible, len(a.sources))

	for i := a.offset; i < end; i++ {
		e := a.sources[i]
		line := renderAbsorbSource(e, width-4)

		if i == a.cursor {
			b.WriteString(selectedItemStyle.Render(" " + line))
		} else {
			b.WriteString(listItemStyle.Render(line))
		}
		if i < end-1 {
			b.WriteString("\n")
		}
	}

	return b.String()
}

func (a absorbModel) visibleCount() int {
	if a.height <= 0 {
		return 20
	}
	return a.height
}

func renderAbsorbSource(e *db.Entity, maxWidth int) string {
	glyph := glyphStyle.Render(display.DisplayGlyph(e.Glyph, e.CardType))

	body := e.Body
	if e.Title != nil {
		body = *e.Title
	}
	if idx := strings.IndexByte(body, '\n'); idx >= 0 {
		body = body[:idx]
	}

	var tags string
	if len(e.Tags) > 0 {
		limit := min(2, len(e.Tags))
		tagParts := make([]string, limit)
		for i := 0; i < limit; i++ {
			tagParts[i] = tagStyle.Render("#" + e.Tags[i])
		}
		tags = " " + strings.Join(tagParts, " ")
	}

	line := fmt.Sprintf("%s %s%s", glyph, body, tags)

	if maxWidth > 0 && len(stripAnsi(line)) > maxWidth {
		body = truncate(body, maxWidth-6)
		line = fmt.Sprintf("%s %s%s", glyph, body, tags)
	}

	return line
}