1 files changed, 83 insertions, 17 deletions

diff --git a/fountain/parse.go b/fountain/parse.go
index a3e1747..c0fff65 100644
--- a/fountain/parse.go
+++ b/fountain/parse.go
@@ -1,46 +1,112 @@
+// Fountain is a Markdown-like language for screenplays and the main inspiration for this tool.
+// Read more at fountain.io
 package fountain
 
 import (
-	"github.com/lapingvino/lexington/lex"
-	"strings"
 	"bufio"
+	"github.com/lapingvino/lexington/lex"
 	"io"
+	"strings"
 )
 
+var Scene = []string{"INT", "EXT", "EST", "INT./EXT", "INT/EXT", "I/E"}
+
+func CheckScene(row string) (bool, string, string) {
+	var scene bool
+	row = strings.ToUpper(row)
+	for _, prefix := range Scene {
+		if strings.HasPrefix(row, prefix+" ") ||
+			strings.HasPrefix(row, prefix+".") {
+			scene = true
+		}
+	}
+	return scene, "scene", row
+}
+
+func CheckTransition(row string) (bool, string, string) {
+	var trans bool
+	row = strings.ToUpper(row)
+	if strings.HasPrefix(row, ">") || strings.HasSuffix(row, " TO:") {
+		trans = true
+	}
+	return trans, "trans", strings.Trim(row, ">< ")
+}
+
+func CheckSynopse(row string) (bool, string, string) {
+	var synopse bool
+	if strings.HasPrefix(row, "=") {
+		synopse = true
+	}
+	return synopse, "synopse", strings.TrimLeft(row, "= ")
+}
+
+func CheckSection(row string) (bool, string, string) {
+	var section bool
+	if strings.HasPrefix(row, "#") {
+		section = true
+	}
+	return section, "section", row
+}
+
+// This is a Fountain parser, trying to be as close as possible to the description
+// found at https://fountain.io/syntax but it can be incomplete.
+// Over time more and more parts should be configurable here, e.g. INT/EXT translatable to other languages.
 func Parse(file io.Reader) (out lex.Screenplay) {
 	var err error
 	var s string
-	var toParse []string
+	var toParse []string // Fill with two to avoid out of bounds when backtracking
 	f := bufio.NewReader(file)
 	for err == nil {
 		s, err = f.ReadString('\n')
 		toParse = append(toParse, s)
 	}
+	toParse = append(toParse, "") // Trigger the backtracking also for the last line
+	out = make(lex.Screenplay, 2, len(toParse))
 	for i, row := range toParse {
-		row = strings.TrimSpace(row)
+		i += 2
+		row = strings.TrimRight(row, "\n\r")
 		action := "action"
 		if row == strings.ToUpper(row) {
 			action = "allcaps"
 		}
 		if row == "" {
 			action = "empty"
-			continue
+
+			// Backtracking for elements that need a following empty line
+			checkfuncs := []func(string) (bool, string, string){
+				CheckScene,
+				CheckTransition,
+				CheckSynopse,
+				CheckSection,
+			}
+			for _, checkfunc := range checkfuncs {
+				check, element, contents := checkfunc(out[i-1].Contents)
+				if check && out[i-2].Contents == "" {
+					out[i-1].Type = element
+					out[i-1].Contents = contents
+					break
+				}
+			}
 		}
-		if i <= 0 {
-			continue
+		if out[i-1].Type != "action" {
+			out[i-1].Contents = strings.TrimSpace(out[i-1].Contents)
 		}
-		switch out[i-1].Type {
-		case "allcaps":
-			out[i-1].Type = "speaker"
-			if row[0] == '(' && row[len(row)-1] == ')' {
-				action = "paren"
-			} else {
-				action = "dialog"
+
+		// Backtracking to check for dialog sequence
+		if row != "" {
+			switch out[i-1].Type {
+			case "allcaps":
+				out[i-1].Type = "speaker"
+				fallthrough
+			case "paren", "dialog":
+				if row[0] == '(' && row[len(row)-1] == ')' {
+					action = "paren"
+				} else {
+					action = "dialog"
+				}
 			}
-		case "paren", "dialog":
-			action = "dialog"
 		}
 		out = append(out, lex.Line{action, row})
 	}
-	return out
+	return out[2:] // Remove the safety empty rows
 }