From 927997d6672af54d4366d5623d11dfb9d126e470 Mon Sep 17 00:00:00 2001
From: Meutel <meutel@meutel.net>
Date: Fri, 30 Dec 2016 16:16:00 +0100
Subject: [PATCH] Paginate books

---
 db.c     | 12 +++++++-----
 extern.h |  2 +-
 main.c   | 14 +++++++++++---
 3 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/db.c b/db.c
index 5c4e69e..15ff038 100644
--- a/db.c
+++ b/db.c
@@ -38,10 +38,10 @@ enum    stmt {
 static const char *const stmts[STMT__MAX] = {
   /* STMT_BOOK */
   "SELECT books.id AS id,title,series_index,name as series_name,series.id AS series_id FROM books LEFT OUTER JOIN books_series_link ON books.id = books_series_link.book LEFT OUTER JOIN series ON series.id = books_series_link.series WHERE books.id = ?",
-  /* STMT_BOOKS */ //TODO offset
-  "SELECT books.id AS id,title,series_index,name as series_name,series.id AS series_id FROM books LEFT OUTER JOIN books_series_link ON books.id = books_series_link.book LEFT OUTER JOIN series ON series.id = books_series_link.series ORDER BY id LIMIT ?",
+  /* STMT_BOOKS */
+  "SELECT books.id AS id,title,series_index,name as series_name,series.id AS series_id FROM books LEFT OUTER JOIN books_series_link ON books.id = books_series_link.book LEFT OUTER JOIN series ON series.id = books_series_link.series ORDER BY id LIMIT ? OFFSET ?",
   /* STMT_BOOKS_AUTHORS */
-  "SELECT authors.id, authors.name, books_authors_link.book as book FROM authors, books_authors_link WHERE books_authors_link.author = authors.id AND books_authors_link.book IN ( SELECT id FROM books ORDER BY id LIMIT ? )",
+  "SELECT authors.id, authors.name, books_authors_link.book as book FROM authors, books_authors_link WHERE books_authors_link.author = authors.id AND books_authors_link.book IN ( SELECT id FROM books ORDER BY id LIMIT ? OFFSET ?)",
 };
 
 /*
@@ -116,9 +116,9 @@ db_book_fill(Book *book, struct ksqlstmt *stmt)
 }
 
 int
-db_books_load(struct kreq *r, BookAdv **books, int limit)
+db_books_load(struct kreq *r, BookAdv **books, int limit, int offset)
 {
-  if (limit < 0) {
+  if (limit < 0 || offset < 0) {
     return 0;
   }
   struct ksqlstmt *stmt;
@@ -131,6 +131,7 @@ db_books_load(struct kreq *r, BookAdv **books, int limit)
             stmts[STMT_BOOKS], 
             STMT_BOOKS);
   ksql_bind_int(stmt, 0, limit);
+  ksql_bind_int(stmt, 1, offset);
   while (KSQL_ROW == ksql_stmt_step(stmt)) {
     books[count] = kcalloc(1, sizeof(BookAdv));
     db_book_fill(&books[count]->b,stmt);
@@ -143,6 +144,7 @@ db_books_load(struct kreq *r, BookAdv **books, int limit)
             stmts[STMT_BOOKS_AUTHORS], 
             STMT_BOOKS_AUTHORS);
   ksql_bind_int(stmt, 0, limit);
+  ksql_bind_int(stmt, 1, offset);
   while (KSQL_ROW == ksql_stmt_step(stmt)) {
     // add author to list, link related book and increment asize
     item = kcalloc(1, sizeof(struct bookauth));
diff --git a/extern.h b/extern.h
index b5a4d55..399ae35 100644
--- a/extern.h
+++ b/extern.h
@@ -60,7 +60,7 @@ typedef struct
 __BEGIN_DECLS
 
 Book *db_book_load(struct kreq *r, int64_t id);
-int db_books_load(struct kreq *r, BookAdv **books, int limit);
+int db_books_load(struct kreq *r, BookAdv **books, int limit, int offset);
 void db_book_free(Book *p);
 void db_book_adv_free(BookAdv *p);
 
diff --git a/main.c b/main.c
index 34ec26c..2615c3c 100644
--- a/main.c
+++ b/main.c
@@ -43,6 +43,8 @@ enum	page {
 
 enum key {
   KEY_ID,
+  KEY_PAGE,
+  KEY_PERPAGE,
   KEY__MAX
 };
 
@@ -55,6 +57,8 @@ static const char *const pages[PAGE__MAX] = {
 
 static const struct kvalid keys[KEY__MAX] = {
   { kvalid_int, "id" }, /* KEY_ID */
+  { kvalid_int, "page" }, /* KEY_PAGE */
+  { kvalid_int, "perpage" }, /* KEY_PERPAGE */
 };
 
 /*
@@ -130,8 +134,12 @@ sendbooks(struct kreq *r)
   const char *errid;
   int64_t id = -1;
   Book *b = NULL;
-  int res, i = 0;
+  int res, i = 0, page = 1, per = 20;
 
+  if (NULL != r->fieldmap[KEY_PAGE])
+    page = r->fieldmap[KEY_PAGE]->parsed.i; 
+  if (NULL != r->fieldmap[KEY_PERPAGE])
+    per = r->fieldmap[KEY_PERPAGE]->parsed.i; 
   if (NULL != r->fieldmap[KEY_ID])
     id = r->fieldmap[KEY_ID]->parsed.i;
   if (r->path[0] != '\0')
@@ -149,8 +157,8 @@ sendbooks(struct kreq *r)
     db_book_free(b);
   } else {
     kjson_array_open(&req);
-    BookAdv **books = kcalloc(200, sizeof(BookAdv));
-    res = db_books_load(r, books, 200);
+    BookAdv **books = kcalloc(per, sizeof(BookAdv));
+    res = db_books_load(r, books, per, per * (page-1));
     while (i < res) {
       Book b = books[i]->b;
       putbook(&req, &b);