package io.oxygenhub.android.ui.code

import androidx.compose.ui.graphics.Color

import androidx.compose.ui.text.AnnotatedString

import androidx.compose.ui.text.SpanStyle

import androidx.compose.ui.text.font.FontWeight

import dev.snipme.highlights.Highlights

import dev.snipme.highlights.model.BoldHighlight

import dev.snipme.highlights.model.ColorHighlight

import dev.snipme.highlights.model.SyntaxLanguage

import dev.snipme.highlights.model.SyntaxThemes

/** The language to highlight a file as, from its name; plain text when unknown. */

fun languageOf(path: String): SyntaxLanguage {

    val name = path.substringAfterLast('/').lowercase()

    return when (name.substringAfterLast('.', "")) {

        "rs" -> SyntaxLanguage.RUST

        "kt", "kts" -> SyntaxLanguage.KOTLIN

        "java" -> SyntaxLanguage.JAVA

        "js", "mjs", "cjs", "jsx" -> SyntaxLanguage.JAVASCRIPT

        "ts", "tsx" -> SyntaxLanguage.TYPESCRIPT

        "py" -> SyntaxLanguage.PYTHON

        "sh", "bash", "zsh" -> SyntaxLanguage.SHELL

        "c", "h" -> SyntaxLanguage.C

        "cc", "cpp", "cxx", "hpp", "hh" -> SyntaxLanguage.CPP

        "go" -> SyntaxLanguage.GO

        "rb" -> SyntaxLanguage.RUBY

        "swift" -> SyntaxLanguage.SWIFT

        "dart" -> SyntaxLanguage.DART

        "cs" -> SyntaxLanguage.CSHARP

        "php" -> SyntaxLanguage.PHP

        "pl", "pm" -> SyntaxLanguage.PERL

        else -> if (name == "makefile" || name == "dockerfile") SyntaxLanguage.SHELL else SyntaxLanguage.DEFAULT

    }

}

/**

 * [code] highlighted for [path], one AnnotatedString per line, so a long

 * file is laid out a line at a time. Plain lines when the language is not

 * known or the file is too long to highlight quickly.

 */

fun highlightLines(code: String, path: String, dark: Boolean): List<AnnotatedString> {

    val lines = code.split('\n')

    val language = languageOf(path)

    if (language == SyntaxLanguage.DEFAULT || code.length > MAX_HIGHLIGHT) return lines.map { AnnotatedString(it) }

    val whole = AnnotatedString.Builder(code)

    val spans = runCatching {

        Highlights.Builder().code(code).language(language).theme(SyntaxThemes.default(dark)).build().getHighlights()

    }.getOrDefault(emptyList())

    for (h in spans) {

        val (start, end) = h.location.start to h.location.end

        if (start < 0 || end > code.length || start >= end) continue

        when (h) {

            is ColorHighlight -> whole.addStyle(SpanStyle(color = Color(0xFF000000.toInt() or h.rgb)), start, end)

            is BoldHighlight -> whole.addStyle(SpanStyle(fontWeight = FontWeight.Bold), start, end)

        }

    }

    val text = whole.toAnnotatedString()

    var at = 0

    return lines.map { line ->

        val piece = text.subSequence(at, at + line.length)

        at += line.length + 1

        piece

    }

}

/** Beyond this many characters a file is shown plain: highlighting it would stall the screen. */

const val MAX_HIGHLIGHT = 200_000