// Copyright ©2020 The go-latex Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mtex

import (
	"strings"

	"github.com/go-latex/latex/ast"
	"github.com/go-latex/latex/tex"
)

type handlerFunc func(p *parser, node ast.Node, state tex.State, math bool) tex.Node

func (h handlerFunc) Handle(p *parser, node ast.Node, state tex.State, math bool) tex.Node {
	return h(p, node, state, math)
}

type handler interface {
	Handle(p *parser, node ast.Node, state tex.State, math bool) tex.Node
}

var (
	builtinMacros = map[string]handler{
		// binary operators
		`\amalg`:           builtinMacro(""),
		`\ast`:             builtinMacro(""),
		`\bigcirc`:         builtinMacro(""),
		`\bigtriangledown`: builtinMacro(""),
		`\bigtriangleup`:   builtinMacro(""),
		`\bullet`:          builtinMacro(""),
		`\cdot`:            builtinMacro(""),
		`\circ`:            builtinMacro(""),
		`\cap`:             builtinMacro(""),
		`\cup`:             builtinMacro(""),
		`\dagger`:          builtinMacro(""),
		`\ddagger`:         builtinMacro(""),
		`\diamond`:         builtinMacro(""),
		`\div`:             builtinMacro(""),
		`\lhd`:             builtinMacro(""),
		`\mp`:              builtinMacro(""),
		`\odot`:            builtinMacro(""),
		`\ominus`:          builtinMacro(""),
		`\oplus`:           builtinMacro(""),
		`\oslash`:          builtinMacro(""),
		`\otimes`:          builtinMacro(""),
		`\pm`:              builtinMacro(""),
		`\rhd`:             builtinMacro(""),
		`\setminus`:        builtinMacro(""),
		`\sqcap`:           builtinMacro(""),
		`\sqcup`:           builtinMacro(""),
		`\star`:            builtinMacro(""),
		`\times`:           builtinMacro(""),
		`\triangleleft`:    builtinMacro(""),
		`\triangleright`:   builtinMacro(""),
		`\uplus`:           builtinMacro(""),
		`\unlhd`:           builtinMacro(""),
		`\unrhd`:           builtinMacro(""),
		`\vee`:             builtinMacro(""),
		`\wedge`:           builtinMacro(""),
		`\wr`:              builtinMacro(""),

		// arithmetic operators
		`\binom`:    builtinMacro("AA"),
		`\dfrac`:    builtinMacro("AA"),
		`\frac`:     builtinMacro("AA"),
		`\stackrel`: builtinMacro("AA"),
		`\tfrac`:    builtinMacro("AA"),
		`\genfrac`:  nil, // FIXME(sbinet)

		// relation symbols
		`\approx`:     builtinMacro(""),
		`\asymp`:      builtinMacro(""),
		`\bowtie`:     builtinMacro(""),
		`\cong`:       builtinMacro(""),
		`\dashv`:      builtinMacro(""),
		`\doteq`:      builtinMacro(""),
		`\doteqdot`:   builtinMacro(""),
		`\dotplus`:    builtinMacro(""),
		`\dots`:       builtinMacro(""),
		`\equiv`:      builtinMacro(""),
		`\frown`:      builtinMacro(""),
		`\geq`:        builtinMacro(""),
		`\gg`:         builtinMacro(""),
		`\in`:         builtinMacro(""),
		`\leq`:        builtinMacro(""),
		`\ll`:         builtinMacro(""),
		`\mid`:        builtinMacro(""),
		`\models`:     builtinMacro(""),
		`\neq`:        builtinMacro(""),
		`\ni`:         builtinMacro(""),
		`\parallel`:   builtinMacro(""),
		`\perp`:       builtinMacro(""),
		`\prec`:       builtinMacro(""),
		`\preceq`:     builtinMacro(""),
		`\propto`:     builtinMacro(""),
		`\sim`:        builtinMacro(""),
		`\simeq`:      builtinMacro(""),
		`\smile`:      builtinMacro(""),
		`\sqsubset`:   builtinMacro(""),
		`\sqsubseteq`: builtinMacro(""),
		`\sqsupset`:   builtinMacro(""),
		`\sqsupseteq`: builtinMacro(""),
		`\subset`:     builtinMacro(""),
		`\subseteq`:   builtinMacro(""),
		`\succ`:       builtinMacro(""),
		`\succeq`:     builtinMacro(""),
		`\supset`:     builtinMacro(""),
		`\supseteq`:   builtinMacro(""),
		`\vdash`:      builtinMacro(""),
		`\Join`:       builtinMacro(""),

		// arrow symbols
		`\downarrow`:          builtinMacro(""),
		`\hookleftarrow`:      builtinMacro(""),
		`\hookrightarrow`:     builtinMacro(""),
		`\leadsto`:            builtinMacro(""),
		`\leftarrow`:          builtinMacro(""),
		`\leftharpoondown`:    builtinMacro(""),
		`\leftharpoonup`:      builtinMacro(""),
		`\leftrightarrow`:     builtinMacro(""),
		`\longleftarrow`:      builtinMacro(""),
		`\longleftrightarrow`: builtinMacro(""),
		`\longmapsto`:         builtinMacro(""),
		`\longrightarrow`:     builtinMacro(""),
		`\rightarrow`:         builtinMacro(""),
		`\mapsto`:             builtinMacro(""),
		`\nearrow`:            builtinMacro(""),
		`\nwarrow`:            builtinMacro(""),
		`\rightharpoondown`:   builtinMacro(""),
		`\rightharpoonup`:     builtinMacro(""),
		`\rightleftharpoons`:  builtinMacro(""),
		`\searrow`:            builtinMacro(""),
		`\swarrow`:            builtinMacro(""),
		`\uparrow`:            builtinMacro(""),
		`\updownarrow`:        builtinMacro(""),
		`\Downarrow`:          builtinMacro(""),
		`\Leftarrow`:          builtinMacro(""),
		`\Leftrightarrow`:     builtinMacro(""),
		`\Longleftarrow`:      builtinMacro(""),
		`\Longleftrightarrow`: builtinMacro(""),
		`\Longrightarrow`:     builtinMacro(""),
		`\Rightarrow`:         builtinMacro(""),
		`\Uparrow`:            builtinMacro(""),
		`\Updownarrow`:        builtinMacro(""),

		// punctuation symbols
		`\ldotp`: builtinMacro(""),
		`\cdotp`: builtinMacro(""),

		// over-under symbols
		`\bigcap`:    builtinMacro(""),
		`\bigcup`:    builtinMacro(""),
		`\bigodot`:   builtinMacro(""),
		`\bigoplus`:  builtinMacro(""),
		`\bigotimes`: builtinMacro(""),
		`\bigsqcup`:  builtinMacro(""),
		`\biguplus`:  builtinMacro(""),
		`\bigvee`:    builtinMacro(""),
		`\bigwedge`:  builtinMacro(""),
		`\coprod`:    builtinMacro(""),
		`\prod`:      builtinMacro(""),
		`\sum`:       builtinMacro(""),

		// over-under functions
		`\lim`:    builtinMacro(""),
		`\liminf`: builtinMacro(""),
		`\limsup`: builtinMacro(""),
		`\max`:    builtinMacro(""),
		`\min`:    builtinMacro(""),
		`\sup`:    builtinMacro(""),

		// dropsub symbols
		`\int`:  builtinMacro(""),
		`\oint`: builtinMacro(""),

		// font names
		`\rm`:      builtinMacro(""),
		`\cal`:     builtinMacro(""),
		`\it`:      builtinMacro(""),
		`\tt`:      builtinMacro(""),
		`\sf`:      builtinMacro(""),
		`\bf`:      builtinMacro(""),
		`\default`: builtinMacro(""),
		`\bb`:      builtinMacro(""),
		`\frak`:    builtinMacro(""),
		`\scr`:     builtinMacro(""),
		`\regular`: builtinMacro(""),

		// function names
		`\arccos`: builtinMacro(""),
		`\arcsin`: builtinMacro(""),
		`\arctan`: builtinMacro(""),
		`\arg`:    builtinMacro(""),
		`\cos`:    builtinMacro(""),
		`\cosh`:   builtinMacro(""),
		`\cot`:    builtinMacro(""),
		`\coth`:   builtinMacro(""),
		`\csc`:    builtinMacro(""),
		`\deg`:    builtinMacro(""),
		`\det`:    builtinMacro(""),
		`\dim`:    builtinMacro(""),
		`\exp`:    builtinMacro("A"),
		`\gcd`:    builtinMacro(""),
		`\hom`:    builtinMacro(""),
		`\inf`:    builtinMacro(""),
		`\ker`:    builtinMacro(""),
		`\lg`:     builtinMacro(""),
		`\ln`:     builtinMacro(""),
		`\log`:    builtinMacro(""),
		`\sec`:    builtinMacro(""),
		`\sin`:    builtinMacro(""),
		`\sinh`:   builtinMacro(""),
		`\sqrt`:   builtinMacro("OA"),
		`\tan`:    builtinMacro(""),
		`\tanh`:   builtinMacro(""),
		`\Pr`:     builtinMacro(""),

		// ambi delim
		`\backslash`: builtinMacro(""),
		`\vert`:      builtinMacro(""),
		`\Vert`:      builtinMacro(""),

		// left delim
		`\{`:      builtinMacro(""),
		`\(`:      builtinMacro(""),
		`(`:       builtinMacro(""),
		`\langle`: builtinMacro(""),
		`\lceil`:  builtinMacro(""),
		`\lfloor`: builtinMacro(""),

		// right delim
		`\}`:      builtinMacro(""),
		`\)`:      builtinMacro(""),
		`)`:       builtinMacro(""),
		`\rangle`: builtinMacro(""),
		`\rceil`:  builtinMacro(""),
		`\rfloor`: builtinMacro(""),

		// symbols
		`\alpha`:   builtinMacro(""),
		`\beta`:    builtinMacro(""),
		`\gamma`:   builtinMacro(""),
		`\delta`:   builtinMacro(""),
		`\iota`:    builtinMacro(""),
		`\epsilon`: builtinMacro(""),
		`\eta`:     builtinMacro(""),
		`\kappa`:   builtinMacro(""),
		`\lambda`:  builtinMacro(""),
		`\mu`:      builtinMacro(""),
		`\nu`:      builtinMacro(""),
		`\omicron`: builtinMacro(""),
		`\pi`:      builtinMacro(""),
		`\theta`:   builtinMacro(""),
		`\xi`:      builtinMacro(""),
		`\rho`:     builtinMacro(""),
		`\sigma`:   builtinMacro(""),
		`\tau`:     builtinMacro(""),
		`\upsilon`: builtinMacro(""),
		`\phi`:     builtinMacro(""),
		`\chi`:     builtinMacro(""),
		`\psi`:     builtinMacro(""),
		`\omega`:   builtinMacro(""),
		`\zeta`:    builtinMacro(""),
		`\Alpha`:   builtinMacro(""),
		`\Beta`:    builtinMacro(""),
		`\Gamma`:   builtinMacro(""),
		`\Delta`:   builtinMacro(""),
		`\Epsilon`: builtinMacro(""),
		`\Zeta`:    builtinMacro(""),
		`\Eta`:     builtinMacro(""),
		`\Theta`:   builtinMacro(""),
		`\Iota`:    builtinMacro(""),
		`\Kappa`:   builtinMacro(""),
		`\Lambda`:  builtinMacro(""),
		`\Mu`:      builtinMacro(""),
		`\Nu`:      builtinMacro(""),
		`\Xi`:      builtinMacro(""),
		`\Omicron`: builtinMacro(""),
		`\Pi`:      builtinMacro(""),
		`\Rho`:     builtinMacro(""),
		`\Sigma`:   builtinMacro(""),
		`\Tau`:     builtinMacro(""),
		`\Upsilon`: builtinMacro(""),
		`\Phi`:     builtinMacro(""),
		`\Chi`:     builtinMacro(""),
		`\Psi`:     builtinMacro(""),
		`\Omega`:   builtinMacro(""),
		`\hbar`:    builtinMacro(""),
		`\nabla`:   builtinMacro(""),

		// math font
		`\mathbf`:      builtinMacro("A"),
		`\mathit`:      builtinMacro("A"),
		`\mathsf`:      builtinMacro("A"),
		`\mathtt`:      builtinMacro("A"),
		`\mathcal`:     builtinMacro("A"),
		`\mathdefault`: builtinMacro("A"),
		`\mathbb`:      builtinMacro("A"),
		`\mathfrak`:    builtinMacro("A"),
		`\mathscr`:     builtinMacro("A"),
		`\mathregular`: builtinMacro("A"),

		// text
		`\textbf`:      builtinMacro("A"),
		`\textit`:      builtinMacro("A"),
		`\textsf`:      builtinMacro("A"),
		`\texttt`:      builtinMacro("A"),
		`\textcal`:     builtinMacro("A"),
		`\textdefault`: builtinMacro("A"),
		`\textbb`:      builtinMacro("A"),
		`\textfrak`:    builtinMacro("A"),
		`\textscr`:     builtinMacro("A"),
		`\textregular`: builtinMacro("A"),

		// space, symbols
		`\ `:      builtinMacro(""),
		`\,`:      builtinMacro(""),
		`\;`:      builtinMacro(""),
		`\!`:      builtinMacro(""),
		`\quad`:   builtinMacro(""),
		`\qquad`:  builtinMacro(""),
		`\:`:      builtinMacro(""),
		`\cdots`:  builtinMacro(""),
		`\ddots`:  builtinMacro(""),
		`\ldots`:  builtinMacro(""),
		`\vdots`:  builtinMacro(""),
		`\hspace`: builtinMacro("A"),

		// catch-all
		//
		`\overline`:     builtinMacro("A"),
		`\operatorname`: builtinMacro("A"),
	}
)

type builtinMacro string

func (m builtinMacro) Handle(p *parser, n ast.Node, state tex.State, math bool) tex.Node {
	node := n.(*ast.Macro)
	if m == "" {
		return tex.NewChar(node.Name.Name, state, math)
	}

	for _, typ := range strings.ToLower(string(m)) {
		switch typ {
		case 'a':
			panic("not implemented")
		case 'o':
			panic("not implemented")
		case 'v':
			panic("not implemented")
		}
	}

	return nil
}