From de3e3e5d4e1e5e182710965f118b8be4e8746eb7 Mon Sep 17 00:00:00 2001
From: Aidan <aidan@aidanis.online>
Date: Thu, 2 Jul 2020 19:35:22 -0700
Subject: [PATCH] file operations in stdlib

---
 stdlib/bool.go    |   2 +-
 stdlib/filesys.go | 148 ++++++++++++++++++++++++++++++++++++++++++++++
 stdlib/stdlib.go  |  28 +++++++++
 3 files changed, 177 insertions(+), 1 deletion(-)

diff --git a/stdlib/bool.go b/stdlib/bool.go
index 5e142bc..328c4e7 100644
--- a/stdlib/bool.go
+++ b/stdlib/bool.go
@@ -43,9 +43,9 @@ func not(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
 
 func eq(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
     out := ast.TRUE
-    second := in.Next
 
     in = in.Eval(ft, vt, false)
+    second := in.Next
 
     if in.Tag != second.Tag {
         out = ast.FALSE
diff --git a/stdlib/filesys.go b/stdlib/filesys.go
index 83a45ef..6504221 100644
--- a/stdlib/filesys.go
+++ b/stdlib/filesys.go
@@ -19,10 +19,33 @@ package stdlib
 
 import (
     "os"
+    "io/ioutil"
     "gitlab.com/whom/shs/ast"
     "gitlab.com/whom/shs/log"
 )
 
+/* Take a path, return the absolute path
+ * does not verify that the absolute path is correct
+ * currently only supports paths using forward slashes
+ *
+ * TODO: handle ~
+ */
+func AbsPath(arg string) string {
+    if arg[0] != '/' {
+        dir, err := os.Getwd()
+        if err != nil {
+            log.Log(log.ERR,
+                "Couldnt get working directory: " + err.Error(),
+                "path")
+            return arg
+        }
+
+        return dir + "/" + arg
+    }
+
+    return arg
+}
+
 func cd(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
     in = in.Eval(ft, vt, true)
 
@@ -44,3 +67,128 @@ func cd(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
     }
     return nil
 }
+
+func fexists(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
+    in = in.Eval(ft, vt, false)
+    if in == nil || (in.Tag != ast.NUMBER && in.Tag != ast.STRING) {
+        log.Log(log.ERR, 
+            "argument to fexists must be a string or number",
+            "fexists")
+        return nil
+    }
+
+    filename := in.Value()
+    out := ast.TRUE
+
+    if _, err := os.Stat(AbsPath(filename)); err != nil {
+        log.Log(log.DEBUG,
+            "couldnt stat file: " + err.Error(),
+            "fexists")
+        out = ast.FALSE
+    }
+
+    ret := &ast.Token{Tag: ast.BOOL}
+    ret.Set(out)
+    return ret
+}
+
+func fread(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
+    in = in.Eval(ft, vt, false)
+    exists := fexists(in, vt, ft) // some waste, extra use of Eval
+    if exists == nil || exists.Tag != ast.BOOL || exists.Value() == ast.FALSE {
+        log.Log(log.ERR,
+            "error calling fexists or file doesnt exist",
+            "fread")
+        return nil
+    }
+
+    fname := in.Value()
+    text, err := ioutil.ReadFile(fname)
+    if err != nil {
+        log.Log(log.ERR,
+            "error reading file" + err.Error(),
+            "fread")
+        return nil
+    }
+
+    ret := &ast.Token{Tag: ast.STRING}
+    ret.Set(string(text))
+    return ret
+}
+
+func fwrite(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
+    in = in.Eval(ft, vt, false)
+    if in == nil || in.Tag == ast.SYMBOL || in.Tag == ast.LIST {
+        log.Log(log.ERR,
+            "first argument must be a filename",
+            "fwrite")
+        return nil
+    }
+
+    text := in.Next
+    if text == nil || text.Tag == ast.SYMBOL || text.Tag == ast.LIST {
+        log.Log(log.ERR,
+            "second argument must be stringable",
+            "fwrite")
+        return nil
+    }
+
+    err := ioutil.WriteFile(
+        AbsPath(in.Value()),
+        []byte(text.Value()),
+        0644)
+    if err != nil {
+        log.Log(log.ERR,
+            "error writing file: " + err.Error(),
+            "fwrite")
+    }
+
+    return nil
+}
+
+func fappend(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
+    in = in.Eval(ft, vt, false)
+    if in == nil || in.Tag == ast.SYMBOL || in.Tag == ast.LIST {
+        log.Log(log.ERR,
+            "first argument must be a filename",
+            "fappend")
+        return nil
+    }
+
+    text := in.Next
+    if text == nil || text.Tag == ast.SYMBOL || text.Tag == ast.LIST {
+        log.Log(log.ERR,
+            "second argument must be stringable",
+            "fappend")
+        return nil
+    }
+
+    exists := fexists(in, vt, ft)
+    if exists.Value() == ast.FALSE {
+        log.Log(log.ERR,
+            "file "+in.Value()+" does not exist",
+            "fappend")
+        return nil
+    }
+
+
+    f, err := os.OpenFile(
+        AbsPath(in.Value()),
+        os.O_APPEND|os.O_CREATE|os.O_WRONLY,
+        0644)
+    if err != nil {
+        log.Log(log.ERR,
+            "couldnt open file for append: " + err.Error(),
+            "fappend")
+        return nil
+    }
+    defer f.Close()
+
+    if _, err := f.WriteString(text.Value()); err != nil {
+        log.Log(log.ERR,
+            "error appending to file: " + err.Error(),
+            "fappend")
+    }
+
+    return nil
+}
diff --git a/stdlib/stdlib.go b/stdlib/stdlib.go
index acb74ee..c0b9c0f 100644
--- a/stdlib/stdlib.go
+++ b/stdlib/stdlib.go
@@ -232,6 +232,34 @@ func GenFuncTable() ast.FuncTable {
             TimesCalled:       0,
             Args:              1,
         },
+
+        "fexists": &ast.Function{
+            Function:    fexists,
+            Name:  "file exists",
+            TimesCalled:       0,
+            Args:              1,
+        },
+
+        "fread": &ast.Function{
+            Function:      fread,
+            Name:    "read file",
+            TimesCalled:       0,
+            Args:              1,
+        },
+
+        "fwrite": &ast.Function{
+            Function:     fwrite,
+            Name:   "write file",
+            TimesCalled:       0,
+            Args:              2,
+        },
+
+        "fappend": &ast.Function{
+            Function:     fappend,
+            Name:"append to file",
+            TimesCalled:        0,
+            Args:               2,
+        },
     }
 
     return stdlib