package tui

import (
	"fmt"
	"strings"

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

type tagRailModel struct {
	tags      []db.TagCount
	cursor    int
	offset    int
	height    int
	width     int
	activeTag string
}

func newTagRailModel() tagRailModel {
	return tagRailModel{}
}

func (r *tagRailModel) setTags(tags []db.TagCount) {
	r.tags = tags
	if r.cursor >= len(tags) {
		r.cursor = max(0, len(tags)-1)
	}
}

func (r *tagRailModel) setSize(width, height int) {
	r.width = width
	r.height = height
}

func (r tagRailModel) selectedTag() string {
	if len(r.tags) == 0 || r.cursor >= len(r.tags) {
		return ""
	}
	return r.tags[r.cursor].Tag
}

func (r tagRailModel) update(key string) tagRailModel {
	switch key {
	case "up", "k":
		if r.cursor > 0 {
			r.cursor--
			if r.cursor < r.offset {
				r.offset = r.cursor
			}
		}
	case "down", "j":
		if r.cursor < len(r.tags)-1 {
			r.cursor++
			visible := r.visibleCount()
			if r.cursor >= r.offset+visible {
				r.offset = r.cursor - visible + 1
			}
		}
	}
	return r
}

func (r tagRailModel) visibleCount() int {
	v := r.height - 2
	if v <= 0 {
		return 10
	}
	return v
}

func (r tagRailModel) view(focused bool) string {
	w := r.width
	if w <= 0 {
		return ""
	}

	var b strings.Builder

	headerStyle := railHeaderStyle
	if focused {
		headerStyle = headerStyle.Foreground(highlight)
	}
	b.WriteString(headerStyle.Render("tags"))
	b.WriteString("\n")
	b.WriteString(separatorStyle.Render(strings.Repeat("─", w)))
	b.WriteString("\n")

	if len(r.tags) == 0 {
		b.WriteString(hintDescStyle.Render(" no tags"))
		return b.String()
	}

	visible := r.visibleCount()
	end := min(r.offset+visible, len(r.tags))

	countW := 0
	for _, tc := range r.tags {
		cw := len(fmt.Sprintf("%d", tc.Count))
		if cw > countW {
			countW = cw
		}
	}

	nameW := w - countW - 3
	if nameW < 4 {
		nameW = 4
	}

	for i := r.offset; i < end; i++ {
		tc := r.tags[i]
		name := "#" + tc.Tag
		if len(name) > nameW {
			name = name[:nameW-1] + "…"
		}

		count := fmt.Sprintf("%*d", countW, tc.Count)
		gap := w - len(name) - len(count) - 1
		if gap < 1 {
			gap = 1
		}

		var line string
		if i == r.cursor && focused {
			line = selectedItemStyle.Render(" " + name + strings.Repeat(" ", gap) + railCountStyle.Render(count))
		} else if tc.Tag == r.activeTag {
			line = " " + railActiveTagStyle.Render(name) + strings.Repeat(" ", gap) + railCountStyle.Render(count)
		} else {
			line = " " + railTagStyle.Render(name) + strings.Repeat(" ", gap) + railCountStyle.Render(count)
		}

		b.WriteString(line)
		if i < end-1 {
			b.WriteString("\n")
		}
	}

	return b.String()
}