package gold

import (
	"fmt"

	"github.com/lucasb-eyer/go-colorful"
)

type StyleType int

const (
	Document StyleType = iota
	BlockQuote
	List
	Item
	Enumeration
	Paragraph
	Heading
	HorizontalRule
	Emph
	Strong
	Del
	Link
	LinkText
	Image
	ImageText
	Text
	HTMLBlock
	CodeBlock
	Softbreak
	Hardbreak
	Indent
	Code
	HTMLSpan
	Table
	TableCell
	TableHead
	TableBody
	TableRow
)

type ElementStyle struct {
	Color           string `json:"color"`
	BackgroundColor string `json:"background_color"`
	Underline       bool   `json:"underline"`
	Bold            bool   `json:"bold"`
	Italic          bool   `json:"italic"`
	CrossedOut      bool   `json:"crossed_out"`
	Faint           bool   `json:"faint"`
	Conceal         bool   `json:"conceal"`
	Overlined       bool   `json:"overlined"`
	Inverse         bool   `json:"inverse"`
	Blink           bool   `json:"blink"`
	Indent          uint   `json:"indent"`
	Margin          uint   `json:"margin"`
	Theme           string `json:"theme"`
	Prefix          string `json:"prefix"`
	Suffix          string `json:"suffix"`
}

func cascadeStyle(parent *ElementStyle, child *ElementStyle) *ElementStyle {
	if parent == nil {
		return child
	}

	s := ElementStyle{}
	if child != nil {
		s = *child
	}

	s.Color = parent.Color
	s.BackgroundColor = parent.BackgroundColor

	if child != nil {
		if child.Color != "" {
			s.Color = child.Color
		}
		if child.BackgroundColor != "" {
			s.BackgroundColor = child.BackgroundColor
		}
	}

	return &s
}

func hexToANSIColor(h string) (int, error) {
	c, err := colorful.Hex(h)
	if err != nil {
		return 0, err
	}

	v2ci := func(v float64) int {
		if v < 48 {
			return 0
		}
		if v < 115 {
			return 1
		}
		return int((v - 35) / 40)
	}

	// Calculate the nearest 0-based color index at 16..231
	r := v2ci(c.R * 255.0) // 0..5 each
	g := v2ci(c.G * 255.0)
	b := v2ci(c.B * 255.0)
	ci := 36*r + 6*g + b /* 0..215 */

	// Calculate the represented colors back from the index
	i2cv := [6]int{0, 0x5f, 0x87, 0xaf, 0xd7, 0xff}
	cr := i2cv[r] // r/g/b, 0..255 each
	cg := i2cv[g]
	cb := i2cv[b]

	// Calculate the nearest 0-based gray index at 232..255
	var grayIdx int
	average := (r + g + b) / 3
	if average > 238 {
		grayIdx = 23
	} else {
		grayIdx = (average - 3) / 10 // 0..23
	}
	gv := 8 + 10*grayIdx // same value for r/g/b, 0..255

	// Return the one which is nearer to the original input rgb value
	c2 := colorful.Color{float64(cr) / 255.0, float64(cg) / 255.0, float64(cb) / 255.0}
	g2 := colorful.Color{float64(gv) / 255.0, float64(gv) / 255.0, float64(gv) / 255.0}
	colorDist := c.DistanceLab(c2)
	grayDist := c.DistanceLab(g2)

	if colorDist <= grayDist {
		return 16 + ci, nil
	}
	return 232 + grayIdx, nil
}

func keyToType(key string) (StyleType, error) {
	switch key {
	case "document":
		return Document, nil
	case "block_quote":
		return BlockQuote, nil
	case "list":
		return List, nil
	case "item":
		return Item, nil
	case "enumeration":
		return Enumeration, nil
	case "paragraph":
		return Paragraph, nil
	case "heading":
		return Heading, nil
	case "hr":
		return HorizontalRule, nil
	case "emph":
		return Emph, nil
	case "strong":
		return Strong, nil
	case "del":
		return Del, nil
	case "link":
		return Link, nil
	case "link_text":
		return LinkText, nil
	case "image":
		return Image, nil
	case "image_text":
		return ImageText, nil
	case "text":
		return Text, nil
	case "html_block":
		return HTMLBlock, nil
	case "code_block":
		return CodeBlock, nil
	case "softbreak":
		return Softbreak, nil
	case "hardbreak":
		return Hardbreak, nil
	case "indent":
		return Indent, nil
	case "code":
		return Code, nil
	case "html_span":
		return HTMLSpan, nil
	case "table":
		return Table, nil
	case "table_cel":
		return TableCell, nil
	case "table_head":
		return TableHead, nil
	case "table_body":
		return TableBody, nil
	case "table_row":
		return TableRow, nil

	default:
		return 0, fmt.Errorf("Invalid style element type: %s", key)
	}
}