permalinks working

experimental/webtry/webtry.go

 package main
 
 import (
         "bytes"
         "crypto/md5"
         "database/sql"
         "encoding/base64"
         "encoding/json"
         "flag"
         "fmt"
         _ "github.com/go-sql-driver/mysql"
+        _ "github.com/mattn/go-sqlite3"
+        htemplate "html/template"
         "io/ioutil"
         "log"
         "net/http"
         "os"
         "os/exec"
         "path/filepath"
+        "regexp"
         "strings"
         "text/template"
 )
 
 const (
         RESULT_COMPILE = `c++ -DSK_GAMMA_SRGB -DSK_GAMMA_APPLY_TO_A8 -DSK_SCALAR_TO_FLOAT_EXCLUDED -DSK_ALLOW_STATIC_GLOBAL_INITIALIZERS=1 -DSK_SUPPORT_GPU=0 -DSK_SUPPORT_OPENCL=0 -DSK_FORCE_DISTANCEFIELD_FONTS=0 -DSK_SCALAR_IS_FLOAT -DSK_CAN_USE_FLOAT -DSK_SAMPLES_FOR_X -DSK_BUILD_FOR_UNIX -DSK_USE_POSIX_THREADS -DSK_SYSTEM_ZLIB=1 -DSK_DEBUG -DSK_DEVELOPER=1 -I../../src/core -I../../src/images -I../../tools/flags -I../../include/config -I../../include/core -I../../include/pathops -I../../include/pipe -I../../include/effects -I../../include/ports -I../../src/sfnt -I../../include/utils -I../../src/utils -I../../include/images -g -fno-exceptions -fstrict-aliasing -Wall -Wextra -Winit-self -Wpointer-arith -Wno-unused-parameter -Wno-c++11-extensions -Werror -m64 -fno-rtti -Wnon-virtual-dtor -c ../../../cache/%s.cpp -o ../../../cache/%s.o`
         LINK           = `c++ -m64 -lstdc++ -lm -o ../../../inout/%s -Wl,--start-group ../../../cache/%s.o obj/experimental/webtry/webtry.main.o obj/gyp/libflags.a libskia_images.a libskia_core.a libskia_effects.a obj/gyp/libjpeg.a obj/gyp/libwebp_dec.a obj/gyp/libwebp_demux.a obj/gyp/libwebp_dsp.a obj/gyp/libwebp_enc.a obj/gyp/libwebp_utils.a libskia_utils.a libskia_opts.a libskia_opts_ssse3.a libskia_ports.a libskia_sfnt.a -Wl,--end-group -lpng -lz -lgif -lpthread -lfontconfig -ldl -lfreetype`
+        DEFAULT_SAMPLE = `SkPaint p;
+p.setColor(SK_ColorRED);
+p.setAntiAlias(true);
+p.setStyle(SkPaint::kStroke_Style);
+p.setStrokeWidth(10);
+
+canvas->drawLine(20, 20, 100, 100, p);
+`
 )
 
 var (
         // codeTemplate is the cpp code template the user's code is copied into.
         codeTemplate *template.Template = nil
 
         // index is the main index.html page we serve.
-        index []byte
+        index *htemplate.Template = nil
 
         // db is the database, nil if we don't have an SQL database to store data into.
         db *sql.DB = nil
+
+        // directLink is the regex that matches URLs paths that are direct links.
+        directLink = regexp.MustCompile("^c/([a-a0-9]+)$")
 )
 
 // flags
 var (
         useChroot = flag.Bool("use_chroot", false, "Run the compiled code in the schroot jail.")
         port      = flag.String("port", ":8000", "HTTP service address (e.g., ':8000')")
 )
 
 // lineNumbers adds #line numbering to the user's code.
 func LineNumbers(c string) string {
         lines := strings.Split(c, "\n")
         ret := []string{}
         for i, line := range lines {
                 ret = append(ret, fmt.Sprintf("#line %d", i+1))
                 ret = append(ret, line)
         }
         return strings.Join(ret, "\n")
 }
 
 func init() {
+
         // Change the current working directory to the directory of the executable.
         var err error
         cwd, err := filepath.Abs(filepath.Dir(os.Args[0]))
         if err != nil {
                 log.Fatal(err)
         }
         os.Chdir(cwd)
 
         codeTemplate, err = template.ParseFiles(filepath.Join(cwd, "templates/template.cpp"))
         if err != nil {
                 panic(err)
         }
-        index, err = ioutil.ReadFile(filepath.Join(cwd, "templates/index.html"))
+        // Convert index.html into a template, which is expanded with the code.
+        index, err = htemplate.ParseFiles(filepath.Join(cwd, "templates/index.html"))
         if err != nil {
                 panic(err)
         }
 
         // Connect to MySQL server. First, get the password from the metadata server.
         // See https://developers.google.com/compute/docs/metadata#custom.
         req, err := http.NewRequest("GET", "http://metadata/computeMetadata/v1/instance/attributes/password", nil)
         if err != nil {
                 panic(err)
         }
         client := http.Client{}
         req.Header.Add("X-Google-Metadata-Request", "True")
         if resp, err := client.Do(req); err == nil {
                 password, err := ioutil.ReadAll(resp.Body)
                 if err != nil {
                         log.Printf("ERROR: Failed to read password from metadata server: %q\n", err)
                         panic(err)
                 }
                 // The IP address of the database is found here:
                 //    https://console.developers.google.com/project/31977622648/sql/instances/webtry/overview
                 // And 3306 is the default port for MySQL.
                 db, err = sql.Open("mysql", fmt.Sprintf("webtry:%s@tcp(173.194.83.52:3306)/webtry", password))
                 if err != nil {
                         log.Printf("ERROR: Failed to open connection to SQL server: %q\n", err)
                         panic(err)
                 }
         } else {
+                // Fallback to sqlite for local use.
+                db, err = sql.Open("sqlite3", "./webtry.db")
+                if err != nil {
+                        log.Printf("ERROR: Failed to open: %q\n", err)
+                        panic(err)
+                }
+                sql := `CREATE TABLE webtry (
+             code      TEXT      DEFAULT ''                 NOT NULL,
+             create_ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP  NOT NULL,
+             hash      CHAR(64)  DEFAULT ''                 NOT NULL,
+             PRIMARY KEY(hash)
+            )`
+                db.Exec(sql)
                 log.Printf("INFO: Failed to find metadata, unable to connect to MySQL server (Expected when running locally): %q\n", err)
         }
 }
 
 // userCode is used in template expansion.
 type userCode struct {
         UserCode string
 }
 
 // expandToFile expands the template and writes the result to the file.
 func expandToFile(filename string, code string, t *template.Template) error {
         f, err := os.Create(filename)
         if err != nil {
                 return err
         }
         defer f.Close()
-        return t.Execute(f, struct{ UserCode string }{UserCode: code})
+        return t.Execute(f, userCode{UserCode: code})
 }
 
 // expandCode expands the template into a file and calculate the MD5 hash.
 func expandCode(code string) (string, error) {
         h := md5.New()
         h.Write([]byte(code))
         hash := fmt.Sprintf("%x", h.Sum(nil))
         // At this point we are running in skia/experimental/webtry, making cache a
         // peer directory to skia.
         // TODO(jcgregorio) Make all relative directories into flags.
         err := expandToFile(fmt.Sprintf("../../../cache/%s.cpp", hash), code, codeTemplate)
         return hash, err
 }
 
 // response is serialized to JSON as a response to POSTs.
 type response struct {
         Message string `json:"message"`
         Img     string `json:"img"`
+        Hash    string `json:"hash"`
 }
 
 // doCmd executes the given command line string in either the out/Debug
 // directory or the inout directory. Returns the stdout, and stderr in the case
 // of a non-zero exit code.
 func doCmd(commandLine string, moveToDebug bool) (string, error) {
         log.Printf("Command: %q\n", commandLine)
         programAndArgs := strings.SplitN(commandLine, " ", 2)
         program := programAndArgs[0]
         args := []string{}
@@ skipping 51 matching lines @@
                 return
         }
         if _, err := db.Exec("INSERT INTO webtry (code, hash) VALUES(?, ?)", code, hash); err != nil {
                 log.Printf("ERROR: Failed to insert code into database: %q\n", err)
         }
 }
 
 // mainHandler handles the GET and POST of the main page.
 func mainHandler(w http.ResponseWriter, r *http.Request) {
         if r.Method == "GET" {
-                w.Write(index)
+                code := DEFAULT_SAMPLE
+                directLink := regexp.MustCompile("^/c/([a-f0-9]+)$")
+                match := directLink.FindStringSubmatch(r.URL.Path)
+                if len(match) == 2 {
+                        hash := match[1]
+                        if db == nil {
+                                http.NotFound(w, r)
+                                return
+                        }
+                        // Update 'code' with the code found in the database.
+                        if err := db.QueryRow("SELECT code FROM webtry WHERE hash=?", hash).Scan(&code); err != nil {
+                                http.NotFound(w, r)
+                                return
+                        }
+                }
+                // Expand the template.
+                if err := index.Execute(w, userCode{UserCode: code}); err != nil {
+                        log.Printf("ERROR: Failed to expand template: %q\n", err)
+                }
         } else if r.Method == "POST" {
                 w.Header().Set("Content-Type", "application/json")
                 b, err := ioutil.ReadAll(r.Body)
                 if err != nil {
                         reportError(w, r, err, "Failed to read a request body.")
                         return
                 }
                 code := string(b)
                 hash, err := expandCode(LineNumbers(code))
                 if err != nil {
@@ skipping 31 matching lines @@
                 }
                 png, err := ioutil.ReadFile("../../../inout/" + hash + ".png")
                 if err != nil {
                         reportError(w, r, err, "Failed to open the generated PNG.")
                         return
                 }
 
                 m := response{
                         Message: message,
                         Img:     base64.StdEncoding.EncodeToString([]byte(png)),
+                        Hash:    hash,
                 }
                 resp, err := json.Marshal(m)
                 if err != nil {
                         reportError(w, r, err, "Failed to serialize a response.")
                         return
                 }
                 w.Write(resp)
         }
 }
 
 func main() {
         flag.Parse()
 
         http.HandleFunc("/", mainHandler)
         log.Fatal(http.ListenAndServe(*port, nil))
 }