OC-WEB 2.0: A Web Browser For OpenComputers!

local component = require("component")
local event = require("event")
local internet = require("internet")
local term = require("term")
local unicode = require("unicode")
local computer = require("computer")

local gpu = component.gpu
local hasColor = gpu.getDepth() > 1

local function trim(s)
    return s:match("^%s*(.-)%s*$")
end

local function serialize(tbl)
    local result = {}
    for k, v in pairs(tbl) do
        table.insert(result, k .. "=" .. v)
    end
    return table.concat(result, ",")
end

local function deserialize(str)
    local result = {}
    for pair in str:gmatch("([^,]+)") do
        local k, v = pair:match("(.-)=(.*)")
        result[trim(k)] = trim(v)
    end
    return result
end

local function bootUpScreen()
    term.clear()
    local logo = [[
 ::::::::   ::::::::               :::       ::: :::::::::: :::::::::
:+:    :+: :+:    :+:              :+:       :+: :+:        :+:    :+:
+:+    +:+ +:+                     +:+       +:+ +:+        +:+    +:+
+#+    +:+ +#+       +#++:++#++:++ +#+  +:+  +#+ +#++:++#   +#++:++#+
+#+    +#+ +#+                     +#+ +#+#+ +#+ +#+        +#+    +#+
#+#    #+# #+#    #+#               #+#+# #+#+#  #+#        #+#    #+#
 ########   ########                 ###   ###   ########## #########
    ]]
    term.setCursor(1, 1)
    term.write(logo)
    term.setCursor(1, select(2, term.getCursor()) + 1)
    term.write("Loading...")
    term.setCursor(1, select(2, term.getCursor()) + 2)
    term.write("OC-WEB 2.0: A Web Browser For OpenComputers Coded by nonogamer9")
    os.sleep(3)
end

local function resolveURL(base, relative)
    if not base or not relative then return nil end
    if relative:match("^https?://") then return relative end
    if relative:sub(1, 1) == "/" then
        return base:match("^(https?://[^/]+)") .. relative
    else
        local baseMatch = base:match("^(https?://.*/)") or base:match("^(https?://[^/]+)")
        if baseMatch then
            if baseMatch:sub(-1) ~= "/" then
                baseMatch = baseMatch .. "/"
            end
            return baseMatch .. relative
        else
            return nil
        end
    end
end

local function handleJavaScript(html, currentBaseURL)
    local redirectUrl = html:match("window%.location%s*=%s*['\"](.-)['\"]")
    if redirectUrl then
        return resolveURL(currentBaseURL, redirectUrl)
    end
    return nil
end

local function fetch(url, visited)
    visited = visited or {}
    if visited[url] then
        return false, "Redirect loop detected"
    end
    visited[url] = true

    local headers = {
        ["User-Agent"] = "OpenComputers/2.0 (Compatible; OCWeb/2.0)",
        ["Accept"] = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
    }

    os.sleep(0)

    local handle, err = internet.request(url, nil, headers)
    if not handle then
        return false, "Failed to connect to " .. url .. ": " .. (err or "unknown error")
    end

    local data = ""
    local status, responseHeaders
    local startTime = computer.uptime()
    local chunkCount = 0
    for chunk in handle do
        chunkCount = chunkCount + 1
        if computer.uptime() - startTime > 0.5 or chunkCount % 10 == 0 then
            os.sleep(0)
            startTime = computer.uptime()
        end

        if not status then
            status, responseHeaders = handle.response()
        end
        if chunk then
            data = data .. chunk
        end
    end

    os.sleep(0)

    if status then
        if status >= 400 then
            return false, "HTTP Error: " .. status
        elseif status >= 300 and status < 400 then
            local redirectUrl = responseHeaders and responseHeaders["location"]
            if redirectUrl then
                local resolvedRedirectUrl = resolveURL(url, redirectUrl)
                if resolvedRedirectUrl then
                    print("Redirecting to: " .. resolvedRedirectUrl)
                    os.sleep(0)
                    return fetch(resolvedRedirectUrl, visited)
                else
                    return false, "Invalid redirect URL: " .. redirectUrl
                end
            end
        end
    end

    os.sleep(0)

    local metaRedirectUrl = data:match('<meta%s+http%-equiv="refresh"%s+content=".-;url=(.-)"')
    if metaRedirectUrl then
        local resolvedRedirectUrl = resolveURL(url, metaRedirectUrl)
        if resolvedRedirectUrl then
            print("Meta redirecting to: " .. resolvedRedirectUrl)
            os.sleep(0)  -- Yield before recursive call
            return fetch(resolvedRedirectUrl, visited)
        else
            return false, "Invalid meta redirect URL: " .. metaRedirectUrl
        end
    end

    os.sleep(0)

    local jsRedirectUrl = handleJavaScript(data, url)
    if jsRedirectUrl then
        print("JavaScript redirecting to: " .. jsRedirectUrl)
        os.sleep(0)
        return fetch(jsRedirectUrl, visited)
    end

    return true, data
end

local function parseCSS(cssText)
    local styles = {}
    for selector, properties in cssText:gmatch("([^{]+){([^}]+)}") do
        selector = trim(selector)
        styles[selector] = {}
        for property, value in properties:gmatch("([^:]+):([^;]+)") do
            styles[selector][trim(property)] = trim(value)
        end
        os.sleep(0)
    end
    return styles
end

local function applyStyles(text, styles)
    if styles["color"] then
        local color = tonumber(styles["color"]:match("#(%x+)"), 16) or 0xFFFFFF
        gpu.setForeground(color)
    end
    if styles["background-color"] then
        local bgColor = tonumber(styles["background-color"]:match("#(%x+)"), 16) or 0x000000
        gpu.setBackground(bgColor)
    end
    if styles["font-weight"] == "bold" then
        text = "[B]" .. text .. "[/B]"
    end
    if styles["font-style"] == "italic" then
        text = "[I]" .. text .. "[/I]"
    end
    return text
end

local function parseHTML(html, baseStyles)
    local links = {}
    local styles = baseStyles or {}

    html = html:gsub('style="(.-)"', function(style)
        local inlineStyles = {}
        for property, value in style:gmatch("([^:]+):([^;]+)") do
            inlineStyles[trim(property)] = trim(value)
        end
        return "data-inline-style='" .. serialize(inlineStyles) .. "'"
    end)

    html = html:gsub("<script.->.-</script>", "")
    html = html:gsub("<style.->.-</style>", "")
    html = html:gsub("<b>(.-)</b>", function(content) return "[B]" .. content .. "[/B]" end)
    html = html:gsub("<strong>(.-)</strong>", function(content) return "[B]" .. content .. "[/B]" end)
    html = html:gsub("<i>(.-)</i>", function(content) return "[I]" .. content .. "[/I]" end)
    html = html:gsub("<em>(.-)</em>", function(content) return "[I]" .. content .. "[/I]" end)
    html = html:gsub("<u>(.-)</u>", function(content) return "[U]" .. content .. "[/U]" end)
    html = html:gsub("<a href=\"(.-)\">(.-)</a>", function(href, content)
        table.insert(links, {href = href, content = content})
        return content .. " [" .. #links .. "]"
    end)
    html = html:gsub("<h([1-6])>(.-)</h%1>", function(level, content) return "[H" .. level .. "]" .. content .. "[/H" .. level .. "]" end)
    html = html:gsub("<li>(.-)</li>", function(content) return " * " .. content end)
    html = html:gsub("<br>", "\n")
    html = html:gsub("<p>(.-)</p>", function(content) return "\n\n" .. content .. "\n\n" end)
    html = html:gsub("<div>(.-)</div>", function(content) return content .. "\n" end)

    html = html:gsub("<table>(.-)</table>", function(tableContent)
        local result = "\n"
        for row in tableContent:gmatch("<tr>(.-)</tr>") do
            for cell in row:gmatch("<t[dh]>(.-)</t[dh]>") do
                result = result .. cell .. "\t"
            end
            result = result .. "\n"
        end
        return result
    end)

    html = html:gsub("data%-inline%-style='(.-)'(.-)", function(styleData, content)
        local inlineStyles = deserialize(styleData)
        return applyStyles(content, inlineStyles)
    end)

    html = html:gsub("<.->", "")
    html = html:gsub("&lt;", "<")
    html = html:gsub("&gt;", ">")
    html = html:gsub("&amp;", "&")
    html = html:gsub("&quot;", "\"")
    html = html:gsub("&apos;", "'")
    html = html:gsub("&nbsp;", " ")
    html = html:gsub("&mdash;", "—")

    os.sleep(0)
    return html, links
end

local function display(baseURL, data, links, styles)
    local w, h = gpu.getResolution()
    local bufferIndex = gpu.allocateBuffer(w, h)
    gpu.setActiveBuffer(bufferIndex)

    local lines = {}
    for line in data:gmatch("[^\r\n]+") do
        table.insert(lines, line)
        if #lines % 10 == 0 then
            os.sleep(0)
        end
    end

    local offset = 0
    local contentHeight = h - 1

    local function redraw()
        gpu.setBackground(0x000000)
        gpu.fill(1, 1, w, h, " ")
        for i = 1, contentHeight do
            local line = lines[i + offset] or ""
            line = applyStyles(line, styles["body"] or {})
            for tag, tagStyles in pairs(styles) do
                if tag ~= "body" then
                    line = line:gsub("%[" .. tag .. "%](.-)[/%]", function(content)
                        return applyStyles(content, tagStyles)
                    end)
                end
            end
            gpu.set(1, i, unicode.sub(line, 1, w))
            if i % 5 == 0 then
                os.sleep(0)
            end
        end

        gpu.setBackground(0x333333)
        gpu.fill(1, h, w, 1, " ")
        gpu.set(1, h, "URL: " .. (baseURL or "N/A") .. " | Use Arrow Keys to Scroll, Q to Quit, U to Change URL")
        gpu.setBackground(0x000000)

        gpu.setActiveBuffer(0)
        gpu.bitblt(0, 1, 1, w, h, bufferIndex)
        gpu.setActiveBuffer(bufferIndex)
    end

    redraw()

    while true do
        local eventType, _, _, y, _, scrollDirection = event.pull()
        local needsRedraw = false
        if eventType == "key_down" then
            if y == 200 then
                offset = math.max(0, offset - 1)
                needsRedraw = true
            elseif y == 208 then
                offset = math.min(#lines - contentHeight, offset + 1)
                needsRedraw = true
            elseif y == 16 then
                break
            elseif y == 22 then
                gpu.freeBuffer(bufferIndex)
                return false
            end
        elseif eventType == "scroll" then
            if scrollDirection == 1 then
                offset = math.max(0, offset - 1)
                needsRedraw = true
            elseif scrollDirection == -1 then
                offset = math.min(#lines - contentHeight, offset + 1)
                needsRedraw = true
            end
        elseif eventType == "touch" then
            local lineIndex = y + offset
            if lineIndex <= #lines then
                local line = lines[lineIndex]
                local linkIndex = line:match("%[(%d+)%]$")
                if linkIndex then
                    local link = links[tonumber(linkIndex)]
                    if link and link.href then
                        local resolvedURL = resolveURL(baseURL, link.href)
                        if resolvedURL then
                            print("Opening link: " .. resolvedURL)
                            gpu.freeBuffer(bufferIndex)
                            local success, newData = fetch(resolvedURL)
                            if success then
                                local newStyles = parseCSS(newData:match("<style>(.-)</style>") or "")
                                local newParsedData, newLinks = parseHTML(newData, newStyles)
                                display(resolvedURL, newParsedData, newLinks, newStyles)
                            else
                                print("Error fetching URL: " .. newData)
                            end
                            return
                        else
                            print("Invalid URL: " .. tostring(link.href))
                        end
                    else
                        print("Invalid link at index: " .. linkIndex)
                    end
                end
            end
        end
        if needsRedraw then
            redraw()
        end
        os.sleep(0)
    end

    gpu.freeBuffer(bufferIndex)
end

function main(showBootScreen)
    if showBootScreen then
        bootUpScreen()
    end
    term.clear()
    print("Enter a URL:")
    local url = io.read()
    if not url:match("^https?://") then
        print("Invalid URL. Please include http:// or https://")
    else
        local success, data = fetch(url)
        if success then
            local styles = parseCSS(data:match("<style>(.-)</style>") or "")
            local parsedData, links = parseHTML(data, styles)
            if display(url, parsedData, links, styles) == false then
                main(false)
            end
        else
            print("Error fetching URL: " .. data)
        end
    end
end

main(true)