From b355ac5bf5d6f1a86fe23abde851c64495c40cb5 Mon Sep 17 00:00:00 2001
From: xdrm-brackets <doowap31@gmail.com>
Date: Wed, 7 Nov 2018 22:13:47 +0100
Subject: [PATCH] create internal/buildfile reader+errors | tests for reader
 [only check syntax and extract without command-specific splitting]

---
 internal/buildfile/errors.go      | 14 +++++
 internal/buildfile/reader.go      | 96 +++++++++++++++++++++++++++++++
 internal/buildfile/reader_test.go | 67 +++++++++++++++++++++
 3 files changed, 177 insertions(+)
 create mode 100644 internal/buildfile/errors.go
 create mode 100644 internal/buildfile/reader.go
 create mode 100644 internal/buildfile/reader_test.go

diff --git a/internal/buildfile/errors.go b/internal/buildfile/errors.go
new file mode 100644
index 0000000..d00ffdb
--- /dev/null
+++ b/internal/buildfile/errors.go
@@ -0,0 +1,14 @@
+package buildfile
+
+import (
+	"fmt"
+)
+
+type LineError struct {
+	Line int
+	Err  error
+}
+
+func (le LineError) Error() string {
+	return fmt.Sprintf("line %d | %s", le.Line, le.Err.Error())
+}
diff --git a/internal/buildfile/reader.go b/internal/buildfile/reader.go
new file mode 100644
index 0000000..c6f4047
--- /dev/null
+++ b/internal/buildfile/reader.go
@@ -0,0 +1,96 @@
+package buildfile
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"strings"
+)
+
+var ErrInvalidSyntax = errors.New("invalid instruction format")
+var ErrUnknownInstruction = errors.New("unknown instruction")
+
+type instruction_type byte
+
+const (
+	// INSTALL one or more package(s)
+	INSTALL instruction_type = iota
+	// UPDATE all installed packages candidates
+	UPDATE
+	// REMOVE one or more package(s)
+	REMOVE
+	// SERVICE management (enable, disable, start, stop, restart, reload)
+	SERVICE
+	// CONF edits configuration files
+	CONF
+)
+
+// instruction is self-explanatory
+type instruction struct {
+	Type instruction_type
+	// Sub command instruction-type-specific
+	Sub  []string
+	Args string
+}
+
+// Reader is the buildfile reader
+type Reader struct {
+	// linux distribution to run on
+	distribution string
+	Content      []*instruction
+}
+
+// NewReader creates a new reader for the specified build file and linux distribution
+func NewReader(distro string, buildfile io.Reader) (*Reader, error) {
+
+	r := &Reader{
+		distribution: distro,
+		Content:      make([]*instruction, 0),
+	}
+
+	// read each line
+	l, reader := 0, bufio.NewReader(buildfile)
+	for {
+		l++
+
+		line, err := reader.ReadString('\n')
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return nil, LineError{l, err}
+		}
+		line = strings.Trim(line, " \t\n")
+
+		// check line base syntax 'cmd args...'
+		if len(line) < 5 || len(strings.Trim(line[0:3], " ")) < 3 || line[1] == ' ' || line[3] != ' ' {
+			return nil, LineError{l, ErrInvalidSyntax}
+		}
+
+		// build instruction from line
+		inst := &instruction{
+			Type: INSTALL,
+			Sub:  make([]string, 0),
+			Args: line[4:],
+		}
+
+		switch line[0:3] {
+		case "ins":
+			inst.Type = INSTALL
+		case "upd":
+			inst.Type = UPDATE
+		case "del":
+			inst.Type = REMOVE
+		case "ser":
+			inst.Type = SERVICE
+		case "cnf":
+			inst.Type = CONF
+		default:
+			return nil, LineError{l, ErrUnknownInstruction}
+		}
+
+		r.Content = append(r.Content, inst)
+
+	}
+
+	return r, nil
+}
diff --git a/internal/buildfile/reader_test.go b/internal/buildfile/reader_test.go
new file mode 100644
index 0000000..e388710
--- /dev/null
+++ b/internal/buildfile/reader_test.go
@@ -0,0 +1,67 @@
+package buildfile
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestInstructionSyntax(t *testing.T) {
+	tests := []struct {
+		File string
+		Line int
+		Err  error
+	}{
+		{"ins args\ncnf args\n", 0, nil},
+		{" ins args\ncnf args\n", 0, nil},
+		{"\tins args\ncnf args\n", 0, nil},
+		{" \t ins args\ncnf args\n", 0, nil},
+		{" \t ins args\ncnf args\n", 0, nil},
+
+		{"cmd args\ncmd args\n", 1, ErrUnknownInstruction},
+		{"ins args\ncmd args\n", 2, ErrUnknownInstruction},
+		{" cmd args\ncmd args\n", 1, ErrUnknownInstruction},
+		{"\tcmd args\ncmd args\n", 1, ErrUnknownInstruction},
+		{" \t cmd args\ncmd args\n", 1, ErrUnknownInstruction},
+		{" \t cmd args\ncmd args\n", 1, ErrUnknownInstruction},
+
+		{" md args\ncmd args\n", 1, ErrInvalidSyntax},
+		{"c d args\ncmd args\n", 1, ErrInvalidSyntax},
+		{"cm  args\ncmd args\n", 1, ErrInvalidSyntax},
+
+		{"ins args\n md args\n", 2, ErrInvalidSyntax},
+		{"ins args\nc d args\n", 2, ErrInvalidSyntax},
+		{"ins args\ncm  args\n", 2, ErrInvalidSyntax},
+	}
+
+	for i, test := range tests {
+
+		// create reader
+		buffer := bytes.NewBufferString(test.File)
+		_, err := NewReader("ubuntu", buffer)
+
+		// no error expected
+		if test.Err == nil {
+			if err != nil {
+				lineerr := err.(LineError)
+				t.Errorf("[%d] expect no error, got <%s>", i, lineerr.Err)
+			}
+			continue
+		} else if err == nil {
+			t.Errorf("[%d] expect error <%s>, got none", i, test.Err)
+			continue
+		}
+
+		lineerr := err.(LineError)
+
+		// error expected
+		if lineerr.Err != test.Err {
+			t.Errorf("[%d] expect error <%s>, got <%s>", i, test.Err, lineerr.Err)
+			continue
+		}
+
+		if lineerr.Line != test.Line {
+			t.Errorf("[%d] expect error at line %d, got %d", i, test.Line, lineerr.Line)
+		}
+
+	}
+}