implement redirection handlers, implement data retrieval functions

cmd/web/handlers.go

@@ -1,8 +1,8 @@
 package main
 
 import (
-    "fmt"
-    "errors"
+	"errors"
+	"fmt"
 	"net/http"
 	"text/template"
 
@@ -52,6 +52,17 @@ func (app *application) webmasterCreate(w http.ResponseWriter, r *http.Request)
 }
 
 func (app *application) siteEntryView(w http.ResponseWriter, r *http.Request) {
+    if r.URL.Path == "/sites/view" {
+        entries, err := app.siteEntries.Latest()
+        if err != nil {
+            app.serverError(w, err)
+            return
+        }
+        for _, entry := range entries {
+            fmt.Fprintf(w, "%+v\n", entry)
+        }
+        return
+    }
     id := models.SiteId(r.URL.Query().Get("id"))
 
     siteEntry, err := app.siteEntries.Get(id)
@@ -71,8 +82,37 @@ func (app *application) siteEntryCreate(w http.ResponseWriter, r *http.Request)
 }
 
 func (app *application) nextSiteEntry(w http.ResponseWriter, r *http.Request) {
+    ref := app.cleanUrl(r.Referer())
+    refSite, err := app.siteEntries.GetByUrl(ref)
+    if err != nil {
+        app.serverError(w, err)
+        return
+    }
+    nextSite, err := app.siteEntries.Get(refSite.Next)
+    if err != nil {
+        app.serverError(w, err)
+        app.infoLog.Printf("%+v", nextSite)
+        return
+    }
+    // TODO ping next site to see if it is up
+    w.Header().Set("Location", nextSite.Url)
+    w.WriteHeader(http.StatusFound)
 }
 
 func (app *application) prevSiteEntry(w http.ResponseWriter, r *http.Request) {
+    ref := app.cleanUrl(r.Referer())
+    refSite, err := app.siteEntries.GetByUrl(ref)
+    if err != nil {
+        app.serverError(w, err)
+        return
+    }
+    prevSite, err := app.siteEntries.Get(refSite.Prev)
+    if err != nil {
+        app.serverError(w, err)
+        return
+    }
+    // TODO ping next site to see if it is up
+    w.Header().Set("Location", prevSite.Url)
+    w.WriteHeader(http.StatusFound)
 }
 

cmd/web/helpers.go

@@ -3,7 +3,9 @@ package main
 import (
 	"fmt"
 	"net/http"
+	"path"
 	"runtime/debug"
+	"strings"
 )
 
 func (app *application) serverError(w http.ResponseWriter, err error) {
@@ -20,3 +22,11 @@ func (app *application) clientError(w http.ResponseWriter, status int) {
 func (app *application) notFound(w http.ResponseWriter) {
     app.clientError(w, http.StatusNotFound)
 }
+
+func (app *application) cleanUrl(url string) string {
+    s, _ := strings.CutPrefix(url, "http://")
+    s, _ = strings.CutPrefix(s, "https://")
+    s = path.Base(path.Clean(s))
+    s = "http://" + s
+    return s
+}

cmd/web/routes.go

@@ -12,6 +12,8 @@ func (app *application) routes() *http.ServeMux {
     mux.HandleFunc("/", app.home)
     mux.HandleFunc("/webmasters/view", app.webmasterView)
     mux.HandleFunc("/sites/view", app.siteEntryView)
+    mux.HandleFunc("/next", app.nextSiteEntry)
+    mux.HandleFunc("/prev", app.prevSiteEntry)
 
     return mux
 }

internal/models/siteentry.go

@@ -40,7 +40,7 @@ func (m *SiteEntryModel) Insert(name string, url string, webmaster *Webmaster) (
 
 // Retrieve a SiteEntry from the database by id
 func (m *SiteEntryModel) Get(id SiteId) (*SiteEntry, error) {
-    stmt := `SELECT id, name, url, webmaster, dateAdded FROM siteentries
+    stmt := `SELECT id, name, url, webmaster, dateAdded, next, prev FROM siteentries
     WHERE id = ?`
 
     row := m.DB.QueryRow(stmt, id)
@@ -48,7 +48,7 @@ func (m *SiteEntryModel) Get(id SiteId) (*SiteEntry, error) {
 
     
     var timeStr string
-    err := row.Scan(&s.Id, &s.Name, &s.Url, &s.Webmaster, &timeStr)
+    err := row.Scan(&s.Id, &s.Name, &s.Url, &s.Webmaster, &timeStr, &s.Next, &s.Prev)
     if err != nil {
         if errors.Is(err, sql.ErrNoRows) {
             return nil, ErrNoRecord
@@ -57,7 +57,7 @@ func (m *SiteEntryModel) Get(id SiteId) (*SiteEntry, error) {
         }
     }
     // time is stored as a string in sqlite, so we need to parse it
-    // probably should be something taken care of in the driver
+    // probably is something taken care of in the driver
     dateAdded, err := time.Parse(time.DateTime, timeStr)
     if err != nil {
         return nil, err
@@ -69,7 +69,31 @@ func (m *SiteEntryModel) Get(id SiteId) (*SiteEntry, error) {
 
 // Retrieve a SiteEntry from the database by url
 func (m *SiteEntryModel) GetByUrl(url string) (*SiteEntry, error) {
-    return nil, nil
+    stmt := `SELECT id, name, url, webmaster, dateAdded, next, prev FROM siteentries
+    WHERE url = ?`
+
+    row := m.DB.QueryRow(stmt, url)
+    s := &SiteEntry{}
+
+    
+    var timeStr string
+    err := row.Scan(&s.Id, &s.Name, &s.Url, &s.Webmaster, &timeStr, &s.Next, &s.Prev)
+    if err != nil {
+        if errors.Is(err, sql.ErrNoRows) {
+            return nil, ErrNoRecord
+        } else {
+            return nil, err
+        }
+    }
+    // time is stored as a string in sqlite, so we need to parse it
+    // probably is something taken care of in the driver
+    s.DateAdded, err = time.Parse(time.DateTime, timeStr)
+    if err != nil {
+        return nil, err
+    }
+
+    return s, nil
+
 }
 
 // Update existing SiteEntry with the values of passed entry
@@ -81,3 +105,39 @@ func (m *SiteEntryModel) Update(entry *SiteEntry) error {
 func (m *SiteEntryModel) Delete(entry *SiteEntry) error {
     return nil
 }
+
+// Get latest 
+func (m *SiteEntryModel) Latest() ([]*SiteEntry, error) {
+    stmt := `SELECT id, name, url, webmaster, dateAdded FROM siteentries
+    ORDER BY dateAdded DESC LIMIT 10`
+
+    rows, err := m.DB.Query(stmt)
+    if err != nil {
+        return nil, err
+    }
+
+    defer rows.Close()
+
+    entries := []*SiteEntry{}
+    var timeStr string
+
+    for rows.Next() {
+        s := &SiteEntry{}
+        err = rows.Scan(&s.Id, &s.Name, &s.Url, &s.Webmaster, &timeStr)
+        if err != nil {
+            return nil, err
+        }
+        s.DateAdded, err = time.Parse(time.DateTime, timeStr)
+        if err != nil {
+            return nil, err
+        }
+
+        entries = append(entries, s)
+    }
+
+    if err = rows.Err(); err != nil {
+        return nil, err
+    }
+
+    return entries, nil
+}