1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

//! This module contains the trait [`TransformField`] as well as all types that implement it
//! And [`Field`] enum that can be used to refer to a [`Message`](Message)'s field
//!
//! [Message]: crate::sink::message::Message

pub mod caps;
pub mod extract;
pub mod replace;
pub mod set;
pub mod shorten;
pub mod trim;

pub use self::{
	caps::Caps, extract::Extract, replace::Replace, set::Set, shorten::Shorten, trim::Trim,
};

use async_trait::async_trait;
use std::fmt::Debug;
use url::Url;

use super::{result::TransformResult, Transform};
use crate::{
	action::transform::error::{TransformError, TransformErrorKind},
	entry::Entry,
	error::InvalidUrlError,
	sink::message::Message,
	utils::OptionExt,
};

/// Transform/change the value of a field of an [`Entry `]
pub trait TransformField: Debug + Send + Sync {
	/// Error that may be returned. Returns [`Infallible`](`std::convert::Infallible`) if it never errors
	type Err: Into<TransformErrorKind>;

	/// Transform/change the `field` into a new one or `None` specifying what happens if `None` is returned
	///
	/// # Errors
	/// Refer to implementator's docs. Most of them never error but some do
	fn transform_field(&self, old_val: Option<&str>) -> Result<TransformResult<String>, Self::Err>;
}

// TODO: make a new name
/// A wrapper around a [`TransformField`] that takes a value out of a [`Field`], passes it to the transformator,
/// and processes the result - updating, removing, or retaining the old value of the field as specified by the transformator
#[derive(Debug)]
pub struct TransformFieldWrapper<T>
where
	T: TransformField,
{
	/// The field to transform/change
	pub field: Field,

	/// The transformator that's going to decide what the new value of the field should be
	pub transformator: T,
}

#[async_trait]
impl<T> Transform for TransformFieldWrapper<T>
where
	T: TransformField,
{
	async fn transform(&self, mut entry: Entry) -> Result<Vec<Entry>, TransformError> {
		// old value of the field
		let old_val = match self.field {
			Field::Title => entry.msg.title.take(),
			Field::Body => entry.msg.body.take(),
			Field::Link => entry.msg.link.take().map(|u| u.to_string()),
			Field::Id => entry.id.take().map(|id| id.0),
			Field::ReplyTo => entry.reply_to.take().map(|id| id.0),
			Field::RawContets => entry.raw_contents.take(),
		};

		let new_val = self
			.transformator
			.transform_field(old_val.as_deref())
			.map_err(|kind| TransformError {
				kind: kind.into(),
				original_entry: entry.clone(),
			})?;

		// finalized value of the field. It's the new value that can get replaced with the old value if requested
		let final_val = new_val.get(|| old_val);

		let new_entry = match self.field {
			Field::Title => Entry {
				msg: Message {
					title: final_val,
					..entry.msg
				},
				..entry
			},
			Field::Body => Entry {
				msg: Message {
					body: final_val,
					..entry.msg
				},
				..entry
			},
			Field::Link => {
				let link = final_val.try_map(|s| {
					Url::try_from(s.as_str()).map_err(|e| TransformError {
						kind: TransformErrorKind::FieldLinkTransformInvalidUrl(InvalidUrlError(
							e, s,
						)),
						original_entry: entry.clone(),
					})
				})?;

				Entry {
					msg: Message { link, ..entry.msg },
					..entry
				}
			}
			Field::Id => Entry {
				id: final_val.map(Into::into),
				..entry
			},
			Field::ReplyTo => Entry {
				reply_to: final_val.map(Into::into),
				..entry
			},
			Field::RawContets => Entry {
				raw_contents: final_val,
				..entry
			},
		};

		Ok(vec![new_entry])
	}
}

/// List of all available fields for transformations
#[derive(Clone, Copy, Debug)]
pub enum Field {
	/// [`Message.title`] field
	Title,
	/// [`Message.body`] field
	Body,
	/// [`Message.link`] field
	Link,
	/// [`Entry.id`] field
	Id,
	/// [`Entry.reply_to`] field
	ReplyTo,
	/// [`Entry.raw_contents`] field
	RawContets,
}