From b6eb9eb87bd90a3f66720ecf85f25ca3df6a8c24 Mon Sep 17 00:00:00 2001
From: Paul Duncan <pabs@pablotron.org>
Date: Sun, 22 May 2016 16:58:43 -0400
Subject: add database from old guff

---
 src/guff/database.cr | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 178 insertions(+)
 create mode 100644 src/guff/database.cr

diff --git a/src/guff/database.cr b/src/guff/database.cr
new file mode 100644
index 0000000..6e5906e
--- /dev/null
+++ b/src/guff/database.cr
@@ -0,0 +1,178 @@
+require "sqlite3"
+
+module Guff
+  class Database < ::SQLite3::Database
+    SQL = {
+      table_exists: "
+        SELECT name
+
+          FROM sqlite_master
+
+         WHERE type = 'table'
+           AND name = ?
+      ",
+
+      pragma_foreign_keys: "
+        PRAGMA foreign_keys = true
+      ",
+    }
+
+    def initialize(path)
+      super(path)
+      @savepoint_id = 0_i64
+      query(SQL[:pragma_foreign_keys])
+    end
+
+    def initialize(path, &block : Database ->)
+      super(path)
+      @savepoint_id = 0_i64
+      query(SQL[:pragma_foreign_keys])
+
+      begin
+        block.call(self)
+      ensure
+        close unless closed?
+      end
+    end
+
+    def table_exists?(table : String) : Bool
+      one(SQL[:table_exists], [table]) == table
+    end
+
+    def one(
+      sql  : String,
+      args : Array(String) | Hash(String, String) | Nil = nil
+    )
+      r = nil
+
+      run(sql, args) do |rs|
+        if rs.next
+          r = rs[0].to_s
+        end
+      end
+
+      # return result
+      r
+    end
+
+    def row(
+      sql   : String,
+      args  : Array(String) | Hash(String, String) | Nil = nil
+    )
+      r = nil
+
+      # exec query
+      run(sql, args) do |rs|
+        r = to_row(rs) if rs.next
+      end
+
+      # return result
+      r
+    end
+
+    def all(
+      sql     : String,
+      args    : Array(String) | Hash(String, String) | Nil = nil,
+      &block  : Hash(String, ::SQLite3::Value) -> \
+    )
+      # build statement
+      run(sql, args) do |rs|
+        # walk results
+        while rs.next
+          # build row and pass it to callback
+          block.call(to_row(rs))
+        end
+      end
+
+      nil
+    end
+
+    def query(
+      sql     : String
+    )
+      run(sql, nil) do |rs|
+        # make sure query executes
+        rs.next
+        nil
+      end
+    end
+
+    def query(
+      sql   : String,
+      args  : Array(String) | Hash(String, String) | Nil = nil,
+    )
+      run(sql, args) do |rs|
+        # make sure query executes
+        rs.next
+        nil
+      end
+    end
+
+    #
+    # NOTE: if you pass a block, be sure to call rs.next at least once,
+    # or the query will _not_ execute!!!
+    #
+    def query(
+      sql     : String,
+      args    : Array(String) | Hash(String, String) | Nil = nil,
+      &block  : ::SQLite3::ResultSet -> \
+    )
+      run(sql, args, &block)
+    end
+
+    def transaction(&block)
+      # get next savepoint id
+      id = next_savepoint_id
+
+      begin
+        query("SAVEPOINT %s" % [id])
+        block.call
+      rescue e
+        query("ROLLBACK TO %s" % [id])
+        raise e
+      ensure
+        query("RELEASE %s" % [id])
+      end
+    end
+
+    private def next_savepoint_id : String
+      # increment savepoint counter
+      @savepoint_id += 1
+
+      # return savepoint id
+      "guff_savepoint_%s" % [@savepoint_id]
+    end
+
+    private def run(
+      sql     : String,
+      args    : Hash(String, String),
+      &block  : ::SQLite3::ResultSet -> \
+    )
+      run(sql, [args], &block)
+    end
+
+    private def run(
+      sql     : String,
+      args    : Array(String | Hash(String, String))? = nil,
+      &block  : ::SQLite3::ResultSet -> \
+    )
+      # build statement
+      puts "sql = %s" % [sql]
+      st = prepare(sql)
+
+      # exec and close statement
+      if args && args.size > 0
+        st.execute(args, &block)
+      else
+        st.execute(&block)
+      end
+
+      # return result
+      nil
+    end
+
+    private def to_row(rs)
+      Hash(String, ::SQLite3::Value).zip(rs.columns, rs.to_a)
+    end
+  end
+end
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