Rewrite Upgrade Tool

* Reformat code
* Add download for sqlite-src-*
* Add extract for sqlite source
* Add auto merge of UserAuth module into Amalgamation

.gitignore

@@ -5,3 +5,10 @@
 
 # VSCode
 .vscode
+
+# Exclude from upgrade
+upgrade/*.c
+upgrade/*.h
+
+# Exclude upgrade binary
+upgrade/upgrade

upgrade/upgrade.go

@@ -0,0 +1,218 @@
+// +build !cgo
+// +build upgrade
+
+package main
+
+import (
+	"archive/zip"
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/PuerkitoBio/goquery"
+)
+
+func download(prefix string) (url string, content []byte, err error) {
+	year := time.Now().Year()
+
+	site := "https://www.sqlite.org/download.html"
+	//fmt.Printf("scraping %v\n", site)
+	doc, err := goquery.NewDocument(site)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	doc.Find("a").Each(func(_ int, s *goquery.Selection) {
+		if strings.HasPrefix(s.Text(), prefix) {
+			url = fmt.Sprintf("https://www.sqlite.org/%d/", year) + s.Text()
+		}
+	})
+
+	if url == "" {
+		return "", nil, fmt.Errorf("Unable to find prefix '%s' on sqlite.org", prefix)
+	}
+
+	fmt.Printf("Downloading %v\n", url)
+	resp, err := http.Get(url)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Ready Body Content
+	content, err = ioutil.ReadAll(resp.Body)
+	defer resp.Body.Close()
+	if err != nil {
+		return "", nil, err
+	}
+
+	return url, content, nil
+}
+
+func mergeFile(src string, dst string) error {
+	defer func() error {
+		fmt.Printf("Removing: %s\n", src)
+		err := os.Remove(src)
+
+		if err != nil {
+			return err
+		}
+
+		return nil
+	}()
+
+	// Open destination
+	fdst, err := os.OpenFile(dst, os.O_APPEND|os.O_WRONLY, 0666)
+	if err != nil {
+		return err
+	}
+	defer fdst.Close()
+
+	// Read source content
+	content, err := ioutil.ReadFile(src)
+	if err != nil {
+		return err
+	}
+
+	// Add Additional newline
+	if _, err := fdst.WriteString("\n"); err != nil {
+		return err
+	}
+
+	fmt.Printf("Merging: %s into %s\n", src, dst)
+	if _, err = fdst.Write(content); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func main() {
+	fmt.Println("Go-SQLite3 Upgrade Tool")
+
+	// Download Amalgamation
+	_, amalgamation, err := download("sqlite-amalgamation-")
+	if err != nil {
+		fmt.Println("Failed to download: sqlite-amalgamation; %s", err)
+	}
+
+	// Download Source
+	_, source, err := download("sqlite-src-")
+	if err != nil {
+		fmt.Println("Failed to download: sqlite-src; %s", err)
+	}
+
+	// Create Amalgamation Zip Reader
+	rAmalgamation, err := zip.NewReader(bytes.NewReader(amalgamation), int64(len(amalgamation)))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Create Source Zip Reader
+	rSource, err := zip.NewReader(bytes.NewReader(source), int64(len(source)))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Extract Amalgamation
+	for _, zf := range rAmalgamation.File {
+		var f *os.File
+		switch path.Base(zf.Name) {
+		case "sqlite3.c":
+			f, err = os.Create("sqlite3-binding.c")
+		case "sqlite3.h":
+			f, err = os.Create("sqlite3-binding.h")
+		case "sqlite3ext.h":
+			f, err = os.Create("sqlite3ext.h")
+		default:
+			continue
+		}
+		if err != nil {
+			log.Fatal(err)
+		}
+		zr, err := zf.Open()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		_, err = io.WriteString(f, "#ifndef USE_LIBSQLITE3\n")
+		if err != nil {
+			zr.Close()
+			f.Close()
+			log.Fatal(err)
+		}
+		scanner := bufio.NewScanner(zr)
+		for scanner.Scan() {
+			text := scanner.Text()
+			if text == `#include "sqlite3.h"` {
+				text = `#include "sqlite3-binding.h"`
+			}
+			_, err = fmt.Fprintln(f, text)
+			if err != nil {
+				break
+			}
+		}
+		err = scanner.Err()
+		if err != nil {
+			zr.Close()
+			f.Close()
+			log.Fatal(err)
+		}
+		_, err = io.WriteString(f, "#else // USE_LIBSQLITE3\n // If users really want to link against the system sqlite3 we\n// need to make this file a noop.\n #endif")
+		if err != nil {
+			zr.Close()
+			f.Close()
+			log.Fatal(err)
+		}
+		zr.Close()
+		f.Close()
+		fmt.Printf("Extracted: %v\n", filepath.Base(f.Name()))
+	}
+
+	//Extract Source
+	for _, zf := range rSource.File {
+		var f *os.File
+		switch path.Base(zf.Name) {
+		case "userauth.c":
+			f, err = os.Create("userauth.c")
+		case "sqlite3userauth.h":
+			f, err = os.Create("userauth.h")
+		default:
+			continue
+		}
+		if err != nil {
+			log.Fatal(err)
+		}
+		zr, err := zf.Open()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		_, err = io.Copy(f, zr)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		zr.Close()
+		f.Close()
+		fmt.Printf("extracted %v\n", filepath.Base(f.Name()))
+	}
+
+	// Merge SQLite User Authentication into amalgamation
+	if err := mergeFile("userauth.c", "sqlite3-binding.c"); err != nil {
+		log.Fatal(err)
+	}
+	if err := mergeFile("userauth.h", "sqlite3-binding.h"); err != nil {
+		log.Fatal(err)
+	}
+
+	os.Exit(0)
+}