From 73380b26bc26d29a9d73ce29b276e69d5811b38c Mon Sep 17 00:00:00 2001
From: PoiScript <poiscript@gmail.com>
Date: Wed, 31 Jul 2019 16:00:46 +0800
Subject: [PATCH] feat(export): export Org struct as org

---
 src/elements/mod.rs |   2 +-
 src/export/mod.rs   |   6 +-
 src/export/org.rs   | 219 ++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs          |   2 +-
 src/org.rs          |  20 ++++
 5 files changed, 245 insertions(+), 4 deletions(-)
 create mode 100644 src/export/org.rs

diff --git a/src/elements/mod.rs b/src/elements/mod.rs
index 2ef29ca..2dfe523 100644
--- a/src/elements/mod.rs
+++ b/src/elements/mod.rs
@@ -1,4 +1,4 @@
-//! Org-mode elements module
+//! Org-mode elements
 
 mod block;
 mod clock;
diff --git a/src/export/mod.rs b/src/export/mod.rs
index 80dfa41..9254548 100644
--- a/src/export/mod.rs
+++ b/src/export/mod.rs
@@ -1,5 +1,7 @@
+//! Export `Org` struct to various formats.
+
 pub mod html;
-// pub mod org;
+pub mod org;
 
 pub use html::{DefaultHtmlHandler, HtmlHandler};
-// pub use org::{DefaultOrgHandler, OrgHandler};
+pub use org::{DefaultOrgHandler, OrgHandler};
diff --git a/src/export/org.rs b/src/export/org.rs
new file mode 100644
index 0000000..9e3e082
--- /dev/null
+++ b/src/export/org.rs
@@ -0,0 +1,219 @@
+use crate::elements::Element;
+use std::io::{Error, Write};
+
+pub trait OrgHandler<E: From<Error>> {
+    fn start<W: Write>(&mut self, mut w: W, element: &Element) -> Result<(), E> {
+        use Element::*;
+
+        match element {
+            // container elements
+            Block(block) => {
+                write!(&mut w, "#+BEGIN_{}", block.name)?;
+                if let Some(parameters) = block.args {
+                    write!(&mut w, " {}", parameters)?;
+                }
+                writeln!(&mut w)?;
+            }
+            Bold => write!(w, "*")?,
+            Document => (),
+            DynBlock(dyn_block) => {
+                write!(&mut w, "#+BEGIN: {}", dyn_block.block_name)?;
+                if let Some(parameters) = dyn_block.arguments {
+                    write!(&mut w, " {}", parameters)?;
+                }
+                writeln!(&mut w)?;
+            }
+            Headline => (),
+            List(_list) => (),
+            Italic => write!(w, "/")?,
+            ListItem(list_item) => write!(w, "{}", list_item.bullet)?,
+            Paragraph => (),
+            Section => (),
+            Strike => write!(w, "+")?,
+            Underline => write!(w, "_")?,
+            Drawer(drawer) => writeln!(w, ":{}:", drawer.name)?,
+            // non-container elements
+            BabelCall(_babel_call) => (),
+            InlineSrc(inline_src) => {
+                write!(&mut w, "src_{}", inline_src.lang)?;
+                if let Some(options) = inline_src.options {
+                    write!(&mut w, "[{}]", options)?;
+                }
+                write!(&mut w, "{{{}}}", inline_src.body)?;
+            }
+            Code { value } => write!(w, "~{}~", value)?,
+            FnRef(fn_ref) => {
+                write!(&mut w, "[fn:")?;
+                if let Some(label) = fn_ref.label {
+                    write!(&mut w, "{}", label)?;
+                }
+                if let Some(definition) = fn_ref.definition {
+                    write!(&mut w, ":{}", definition)?;
+                }
+                write!(&mut w, "]")?;
+            }
+            InlineCall(inline_call) => {
+                write!(&mut w, "call_{}", inline_call.name)?;
+                if let Some(header) = inline_call.inside_header {
+                    write!(&mut w, "[{}]", header)?;
+                }
+                write!(&mut w, "({})", inline_call.arguments)?;
+                if let Some(header) = inline_call.end_header {
+                    write!(&mut w, "[{}]", header)?;
+                }
+            }
+            Link(link) => {
+                write!(&mut w, "[[{}]", link.path)?;
+                if let Some(desc) = link.desc {
+                    write!(&mut w, "[{}]", desc)?;
+                }
+                write!(&mut w, "]")?;
+            }
+            Macros(_macros) => (),
+            Planning(_planning) => (),
+            RadioTarget(_radio_target) => (),
+            Snippet(snippet) => write!(w, "@@{}:{}@@", snippet.name, snippet.value)?,
+            Target(_target) => (),
+            Text { value } => write!(w, "{}", value)?,
+            Timestamp(timestamp) => {
+                use crate::elements::{Date, Time, Timestamp::*};
+
+                fn write_date<W: Write>(mut w: W, date: &Date) -> Result<(), Error> {
+                    write!(
+                        w,
+                        "{}-{}-{} {}",
+                        date.year, date.month, date.day, date.dayname
+                    )
+                }
+
+                fn write_time<W: Write>(mut w: W, time: &Option<Time>) -> Result<(), Error> {
+                    if let Some(time) = time {
+                        write!(w, " {}:{}", time.hour, time.minute)
+                    } else {
+                        Ok(())
+                    }
+                }
+
+                match timestamp {
+                    Active {
+                        start_date,
+                        start_time,
+                        ..
+                    } => {
+                        write!(&mut w, "<")?;
+                        write_date(&mut w, start_date)?;
+                        write_time(&mut w, start_time)?;
+                        write!(&mut w, ">")?;
+                    }
+                    Inactive {
+                        start_date,
+                        start_time,
+                        ..
+                    } => {
+                        write!(&mut w, "[")?;
+                        write_date(&mut w, start_date)?;
+                        write_time(&mut w, start_time)?;
+                        write!(&mut w, "]")?;
+                    }
+                    ActiveRange {
+                        start_date,
+                        start_time,
+                        end_date,
+                        end_time,
+                        ..
+                    } => {
+                        write!(&mut w, "<")?;
+                        write_date(&mut w, start_date)?;
+                        write_time(&mut w, start_time)?;
+                        write!(&mut w, ">--<")?;
+                        write_date(&mut w, end_date)?;
+                        write_time(&mut w, end_time)?;
+                        write!(&mut w, ">")?;
+                    }
+                    InactiveRange {
+                        start_date,
+                        start_time,
+                        end_date,
+                        end_time,
+                        ..
+                    } => {
+                        write!(&mut w, "[")?;
+                        write_date(&mut w, start_date)?;
+                        write_time(&mut w, start_time)?;
+                        write!(&mut w, "]--[")?;
+                        write_date(&mut w, end_date)?;
+                        write_time(&mut w, end_time)?;
+                        write!(&mut w, "]")?;
+                    }
+                    Diary(value) => write!(w, "<%%({})>", value)?,
+                }
+            }
+            Verbatim { value } => write!(w, "={}=", value)?,
+            FnDef(_fn_def) => (),
+            Clock(_clock) => (),
+            Comment { value } => write!(w, "{}", value)?,
+            FixedWidth { value } => write!(w, "{}", value)?,
+            Keyword(keyword) => {
+                write!(&mut w, "#+{}", keyword.key)?;
+                if let Some(optional) = keyword.optional {
+                    write!(&mut w, "[{}]", optional)?;
+                }
+                writeln!(&mut w, ": {}", keyword.value)?;
+            }
+            Rule => writeln!(w, "-----")?,
+            Cookie(_cookie) => (),
+            Title(title) => {
+                for _ in 0..title.level {
+                    write!(&mut w, "*")?;
+                }
+                if let Some(keyword) = title.keyword {
+                    write!(&mut w, " {}", keyword)?;
+                }
+                if let Some(priority) = title.priority {
+                    write!(&mut w, " [#{}]", priority)?;
+                }
+                write!(&mut w, " ")?;
+            }
+        }
+
+        Ok(())
+    }
+
+    fn end<W: Write>(&mut self, mut w: W, element: &Element) -> Result<(), E> {
+        use Element::*;
+
+        match element {
+            // container elements
+            Block(block) => writeln!(w, "#+END_{}", block.name)?,
+            Bold => write!(w, "*")?,
+            Document => (),
+            DynBlock(_dyn_block) => writeln!(w, "#+END:")?,
+            Headline => (),
+            List(_list) => (),
+            Italic => write!(w, "/")?,
+            ListItem(_) => (),
+            Paragraph => write!(w, "\n\n")?,
+            Section => (),
+            Strike => write!(w, "+")?,
+            Underline => write!(w, "_")?,
+            Drawer(_) => writeln!(w, ":END:")?,
+            Title(title) => {
+                if !title.tags.is_empty() {
+                    write!(&mut w, " :")?;
+                }
+                for tag in &title.tags {
+                    write!(&mut w, "{}:", tag)?;
+                }
+                writeln!(&mut w)?;
+            }
+            // non-container elements
+            _ => debug_assert!(!element.is_container()),
+        }
+
+        Ok(())
+    }
+}
+
+pub struct DefaultOrgHandler;
+
+impl OrgHandler<Error> for DefaultOrgHandler {}
diff --git a/src/lib.rs b/src/lib.rs
index c431adb..9fe7eb1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -88,7 +88,7 @@
 //! use std::io::{Error as IOError, Write};
 //! use std::string::FromUtf8Error;
 //!
-//! use orgize::export::{html::Escape, DefaultHtmlHandler, HtmlHandler};
+//! use orgize::export::{DefaultHtmlHandler, HtmlHandler};
 //! use orgize::{Element, Org};
 //! use slugify::slugify;
 //!
diff --git a/src/org.rs b/src/org.rs
index ff49de0..3e0cfdc 100644
--- a/src/org.rs
+++ b/src/org.rs
@@ -146,6 +146,26 @@ impl<'a> Org<'a> {
 
         Ok(())
     }
+
+    pub fn org<W: Write>(&self, wrtier: W) -> Result<(), Error> {
+        self.org_with_handler(wrtier, DefaultOrgHandler)
+    }
+
+    pub fn org_with_handler<W, H, E>(&self, mut writer: W, mut handler: H) -> Result<(), E>
+    where
+        W: Write,
+        E: From<Error>,
+        H: OrgHandler<E>,
+    {
+        for event in self.iter() {
+            match event {
+                Event::Start(element) => handler.start(&mut writer, element)?,
+                Event::End(element) => handler.end(&mut writer, element)?,
+            }
+        }
+
+        Ok(())
+    }
 }
 
 fn is_headline(text: &str) -> Option<usize> {