package tui

import (
	"fmt"
	"strings"
	"time"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/glamour"

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

type detailMode int

const (
	detailPreview detailMode = iota
	detailRun
	detailFill
)

type detailModel struct {
	entity    *db.Entity
	backlinks []db.Backlink
	scroll    int
	height    int
	width     int
	mode      detailMode
	run       runModel
	fill      fillModel
}

func newDetailModel() detailModel {
	return detailModel{}
}

func (d *detailModel) setEntity(e *db.Entity) {
	d.entity = e
	d.backlinks = nil
	d.scroll = 0
	d.mode = detailPreview
}

func (d *detailModel) setSize(width, height int) {
	d.width = width
	d.height = height
}

func (d detailModel) update(msg tea.KeyMsg) (detailModel, tea.Cmd) {
	switch d.mode {
	case detailRun:
		d.run = d.run.update(msg.String())
		return d, nil
	case detailFill:
		var cmd tea.Cmd
		d.fill, cmd = d.fill.update(msg)
		return d, cmd
	default:
		switch msg.String() {
		case "up", "k":
			if d.scroll > 0 {
				d.scroll--
			}
		case "down", "j":
			d.scroll++
		case "pgdown", "ctrl+d":
			d.scroll += d.height
		case "pgup", "ctrl+u":
			d.scroll -= d.height
			if d.scroll < 0 {
				d.scroll = 0
			}
		case "home", "g":
			d.scroll = 0
		case "end", "G":
			d.scroll = 1<<31 - 1
		}
		return d, nil
	}
}

func (d detailModel) view(width int) string {
	switch d.mode {
	case detailRun:
		return d.run.view(width)
	case detailFill:
		return d.fill.view(width)
	default:
		return d.previewView(width)
	}
}

func (d detailModel) previewView(width int) string {
	if d.entity == nil {
		return ""
	}

	e := d.entity
	var b strings.Builder

	glyph := display.DisplayGlyph(e.Glyph, e.CardType)
	header := fmt.Sprintf("%s  %s", glyph, display.FormatID(e.ID))
	if e.CardType != nil {
		header += "  " + affordanceStyle.Render(string(*e.CardType))
	}
	b.WriteString(detailHeaderStyle.Render(header))
	b.WriteString("\n\n")

	if e.Title != nil {
		b.WriteString(detailBodyStyle.Render("title: " + *e.Title))
		b.WriteString("\n")
	}

	bodyWidth := width - 4
	if bodyWidth < 20 {
		bodyWidth = 20
	}
	r, _ := glamour.NewTermRenderer(
		glamour.WithStylePath(glamourStyle()),
		glamour.WithWordWrap(bodyWidth),
	)
	rendered, err := r.Render(e.Body)
	if err != nil {
		rendered = e.Body
	}
	rendered = strings.TrimRight(rendered, "\n")
	b.WriteString(detailBodyStyle.Render(rendered))
	b.WriteString("\n")

	if e.CardType != nil {
		cardSection := renderCardData(e)
		if cardSection != "" {
			b.WriteString("\n")
			b.WriteString(cardSection)
		}
	}

	if len(e.Tags) > 0 {
		tagParts := make([]string, len(e.Tags))
		for i, t := range e.Tags {
			tagParts[i] = tagStyle.Render("#" + t)
		}
		b.WriteString("\n")
		b.WriteString(detailBodyStyle.Render(strings.Join(tagParts, " ")))
		b.WriteString("\n")
	}

	if len(d.backlinks) > 0 {
		b.WriteString("\n")
		b.WriteString(detailLabelStyle.Render("  ← backlinks"))
		b.WriteString("\n")
		for _, bl := range d.backlinks {
			label := bl.Body
			if bl.Title != nil {
				label = *bl.Title
			} else if len(label) > 40 {
				label = label[:40] + "…"
			}
			line := "    " + backlinkStyle.Render(label)
			if bl.LinkText != "" {
				line += " " + hintDescStyle.Render("(as \""+bl.LinkText+"\")")
			}
			b.WriteString(line + "\n")
		}
	}

	b.WriteString("\n")
	meta := fmt.Sprintf("created  %s", e.CreatedAt.Format(time.DateTime))
	if e.ModifiedAt != e.CreatedAt {
		meta += fmt.Sprintf("\nmodified %s", e.ModifiedAt.Format(time.DateTime))
	}
	if e.TimeAnchor != nil {
		meta += fmt.Sprintf("\nanchored @%s", *e.TimeAnchor)
	}
	if e.Pinned {
		meta += "\n" + pinnedStyle.Render("pinned")
	}
	if e.CardType != nil {
		meta += fmt.Sprintf("\ncard     %s", *e.CardType)
	}
	if e.UseCount > 0 {
		meta += fmt.Sprintf("\nused     %d×", e.UseCount)
	}
	if e.CompletedAt != nil {
		meta += fmt.Sprintf("\ndone     %s", e.CompletedAt.Format(time.DateTime))
	}
	b.WriteString(idStyle.Render(meta))

	lines := strings.Split(b.String(), "\n")
	totalLines := len(lines)

	maxScroll := totalLines - d.height
	if maxScroll < 0 {
		maxScroll = 0
	}
	scroll := d.scroll
	if scroll > maxScroll {
		scroll = maxScroll
	}

	if totalLines > d.height && d.height > 0 && len(lines) > 0 {
		indicator := idStyle.Render(fmt.Sprintf(" %d/%d", scroll+1, totalLines))
		lines[0] = lines[0] + indicator
	}

	if scroll > 0 && scroll < totalLines {
		lines = lines[scroll:]
	}
	if d.height > 0 && len(lines) > d.height {
		lines = lines[:d.height]
	}

	return strings.Join(lines, "\n")
}

func renderCardData(e *db.Entity) string {
	if e.CardData == nil {
		return ""
	}

	data, err := e.CardDataJSON()
	if err != nil || data == nil {
		return ""
	}

	var b strings.Builder

	switch *e.CardType {
	case db.CardChecklist:
		steps, ok := data["steps"].([]interface{})
		if !ok {
			break
		}
		done := 0
		for _, s := range steps {
			step, ok := s.(map[string]interface{})
			if !ok {
				continue
			}
			text, _ := step["text"].(string)
			isDone, _ := step["done"].(bool)
			if isDone {
				done++
				b.WriteString("  " + checkDoneStyle.Render("[✓] "+text) + "\n")
			} else {
				b.WriteString("  " + checkPendingStyle.Render("[ ] "+text) + "\n")
			}
		}
		progress := fmt.Sprintf("  %d/%d steps", done, len(steps))
		b.WriteString(detailLabelStyle.Render(progress))
		b.WriteString("  " + helpStyle.Render("r:run"))

	case db.CardTemplate:
		slots, ok := data["slots"].([]interface{})
		if !ok {
			break
		}
		b.WriteString(detailLabelStyle.Render("  slots:") + "\n")
		for _, s := range slots {
			slot, ok := s.(map[string]interface{})
			if !ok {
				continue
			}
			name, _ := slot["name"].(string)
			def, _ := slot["default"].(string)
			line := "  ${" + name + "}"
			if def != "" {
				line += "  " + detailValueStyle.Render("default: "+def)
			}
			b.WriteString(line + "\n")
		}
		b.WriteString("  " + helpStyle.Render("f:fill"))

	case db.CardDecision:
		if chose, ok := data["chose"].(string); ok && chose != "" {
			b.WriteString("  " + detailLabelStyle.Render("chose: ") + detailValueStyle.Render(chose) + "\n")
		}
		if why, ok := data["why"].(string); ok && why != "" {
			b.WriteString("  " + detailLabelStyle.Render("why: ") + detailValueStyle.Render(why) + "\n")
		}
		if rejected, ok := data["rejected"].([]interface{}); ok && len(rejected) > 0 {
			items := make([]string, 0, len(rejected))
			for _, r := range rejected {
				if s, ok := r.(string); ok {
					items = append(items, s)
				}
			}
			if len(items) > 0 {
				b.WriteString("  " + detailLabelStyle.Render("rejected: ") + detailValueStyle.Render(strings.Join(items, ", ")) + "\n")
			}
		}

	case db.CardLink:
		if url, ok := data["url"].(string); ok && url != "" {
			b.WriteString("  " + detailLabelStyle.Render("↗ ") + detailValueStyle.Render(url) + "\n")
		}
	}

	return b.String()
}