parse-mediawiki-sql 0.3.0

/*!
Defines the types used in the [`schemas`](crate::schemas) module
and implements the [`FromSql`] trait for these and other types,
so that they can be parsed from SQL syntax.
Re-exports the [`Datelike`] and [`Timelike`] traits from the [`chrono`] crate,
which are used by [`Timestamp`].
*/

use bstr::{BStr, ByteSlice, B};
use joinery::prelude::*;
use nom::{
    branch::alt,
    bytes::streaming::{escaped_transform, is_not, tag},
    character::streaming::{char, digit1, one_of},
    combinator::{map, map_res, opt, recognize},
    error::{context, ErrorKind, ParseError},
    multi::many1,
    number::streaming::recognize_float,
    sequence::{delimited, pair, preceded, terminated, tuple},
};
use ordered_float::NotNan;
use std::{
    collections::BTreeMap,
    fmt::Display,
    iter::FromIterator,
    ops::{Deref, Index},
};

/// The type that [`Timestamp`] derefs to, from `chrono`.
pub use chrono::NaiveDateTime;

/// Trait for [`Timestamp`], re-exported from `chrono`.
pub use chrono::{Datelike, Timelike};

pub type IResult<'a, T> = nom::IResult<&'a [u8], T, Error<'a>>;

/**
Trait for converting from the SQL syntax for a simple type
(anything other than a tuple) to a Rust type,
which can borrow from the string or not.
Used by [`schemas::FromSqlTuple`][crate::FromSqlTuple].
*/
pub trait FromSql<'a>: Sized {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self>;
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub enum ParseTypeContext<'a> {
    Single {
        input: &'a BStr,
        label: &'static str,
    },
    Alternatives {
        input: &'a BStr,
        labels: Vec<&'static str>,
    },
}

impl<'a> ParseTypeContext<'a> {
    fn push(&mut self, other: Self) {
        match self {
            ParseTypeContext::Single { label: label1, .. } => match other {
                ParseTypeContext::Single {
                    input,
                    label: label2,
                } => {
                    *self = ParseTypeContext::Alternatives {
                        input,
                        labels: vec![label1, label2],
                    }
                }
                ParseTypeContext::Alternatives {
                    input,
                    labels: mut labels2,
                } => {
                    labels2.insert(0, label1);
                    *self = ParseTypeContext::Alternatives {
                        input,
                        labels: labels2,
                    }
                }
            },
            ParseTypeContext::Alternatives {
                labels: labels1, ..
            } => match other {
                ParseTypeContext::Single { label: label2, .. } => {
                    labels1.push(label2);
                }
                ParseTypeContext::Alternatives {
                    labels: labels2, ..
                } => {
                    labels1.extend(labels2);
                }
            },
        }
    }
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub enum Error<'a> {
    ErrorKind { input: &'a BStr, kind: ErrorKind },
    ErrorWithContexts(Vec<ParseTypeContext<'a>>),
}

impl<'a> ParseError<&'a [u8]> for Error<'a> {
    fn from_error_kind(input: &'a [u8], kind: ErrorKind) -> Self {
        Self::ErrorKind {
            input: input.into(),
            kind,
        }
    }

    // Bubble up ErrorWithContext and skip ErrorKind.
    fn append(input: &'a [u8], kind: ErrorKind, other: Self) -> Self {
        match other {
            Self::ErrorKind { .. } => Self::from_error_kind(input, kind),
            e @ Self::ErrorWithContexts(_) => e,
        }
    }

    fn from_char(input: &'a [u8], _: char) -> Self {
        Self::from_error_kind(input, ErrorKind::Char)
    }

    fn or(self, other: Self) -> Self {
        match self {
            Error::ErrorKind { .. } => match other {
                Error::ErrorKind { input, kind } => {
                    Self::from_error_kind(input, kind)
                }
                e @ Error::ErrorWithContexts(_) => e,
            },
            Error::ErrorWithContexts(mut contexts) => match other {
                Error::ErrorKind { .. } => Error::ErrorWithContexts(contexts),
                Error::ErrorWithContexts(mut other_contexts) => {
                    if let (Some(mut old_context), Some(new_context)) =
                        (contexts.pop(), other_contexts.pop())
                    {
                        old_context.push(new_context);
                        other_contexts.push(old_context);
                    };
                    Error::ErrorWithContexts(other_contexts)
                }
            },
        }
    }

    fn add_context(input: &'a [u8], label: &'static str, other: Self) -> Self {
        let context = ParseTypeContext::Single {
            input: input.into(),
            label,
        };
        match other {
            Self::ErrorKind { .. } => Self::ErrorWithContexts(vec![context]),
            Self::ErrorWithContexts(mut contexts) => {
                contexts.push(context);
                Self::ErrorWithContexts(contexts)
            }
        }
    }
}

const INPUT_GRAPHEMES_TO_SHOW: usize = 50;

impl<'a> Display for Error<'a> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        fn show_input(input: &BStr) -> &BStr {
            // Try to display the whole SQL tuple.
            if input.get(0) == Some(&b'(') {
                let row = recognize(delimited(
                    char('('),
                    many1(pair(
                        alt((
                            tag("NULL"),
                            recognize(f64::from_sql),
                            recognize(i64::from_sql),
                            recognize(<Vec<u8>>::from_sql),
                        )),
                        opt(char(',')),
                    )),
                    char(')'),
                ))(input);

                if let Ok((_, row)) = row {
                    return row.into();
                }
            }
            alt((
                tag("NULL"),
                recognize(f64::from_sql),
                recognize(i64::from_sql),
                recognize(<Vec<u8>>::from_sql),
            ))(input)
            .map(|(_, result)| result.into())
            .unwrap_or_else(|_| {
                input
                    .grapheme_indices()
                    .nth(INPUT_GRAPHEMES_TO_SHOW)
                    .map(|(_, end, _)| &input[..end])
                    .unwrap_or(input)
            })
        }

        match self {
            Error::ErrorKind { input, kind } => write!(
                f,
                "error in {} combinator at\n\t{}",
                kind.description(),
                show_input(input),
            ),
            Error::ErrorWithContexts(contexts) => {
                match contexts.as_slice() {
                    [] => {
                        write!(f, "unknown error")?;
                    }
                    [first, rest @ ..] => {
                        let mut last_input = match first {
                            ParseTypeContext::Single { input, label } => {
                                write!(
                                    f,
                                    "expected {} at\n\t{}\n",
                                    label,
                                    show_input(input),
                                )?;
                                input
                            }
                            ParseTypeContext::Alternatives {
                                input,
                                labels,
                            } => {
                                write!(
                                    f,
                                    "expected {} at \n\t{}\n",
                                    labels.into_iter().join_with(" or "),
                                    show_input(input),
                                )?;
                                input
                            }
                        };
                        for context in rest {
                            let labels_joined;
                            let (displayed_label, input): (&dyn Display, _) =
                                match context {
                                    ParseTypeContext::Single {
                                        input,
                                        label,
                                    } => {
                                        let displayed_input =
                                            if last_input == input {
                                                None
                                            } else {
                                                Some(input)
                                            };
                                        last_input = input;
                                        (label, displayed_input)
                                    }
                                    ParseTypeContext::Alternatives {
                                        input,
                                        labels,
                                    } => {
                                        let displayed_input =
                                            if last_input == input {
                                                None
                                            } else {
                                                Some(input)
                                            };
                                        labels_joined = labels
                                            .into_iter()
                                            .join_with(" or ");
                                        last_input = input;
                                        (&labels_joined, displayed_input)
                                    }
                                };
                            write!(f, "while parsing {}", displayed_label,)?;
                            if let Some(input) = input {
                                write!(f, " at\n\t{}", show_input(input),)?;
                            }
                            write!(f, "\n")?;
                        }
                    }
                }
                Ok(())
            }
        }
    }
}

impl<'a> FromSql<'a> for bool {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        context("1 or 0", map(one_of("01"), |b| b == '1'))(s)
    }
}

// This won't panic if the SQL file is valid and the parser is using
// the correct numeric types.
macro_rules! number_impl {
    ($type_name:ty $implementation:block ) => {
        impl<'a> FromSql<'a> for $type_name {
            fn from_sql(s: &'a [u8]) -> IResult<'a, $type_name> {
                context(
                    concat!("number (", stringify!($type_name), ")"),
                    map($implementation, |num: &[u8]| {
                        std::str::from_utf8(num)
                            .expect(concat!(
                                "valid UTF-8 in ",
                                stringify!($type_name)
                            ))
                            .parse()
                            .expect(concat!("valid ", stringify!($type_name)))
                    }),
                )(s)
            }
        }
    };
    ($type_name:ty $implementation:block $further_processing:block ) => {
        impl<'a> FromSql<'a> for $type_name {
            fn from_sql(s: &'a [u8]) -> IResult<'a, $type_name> {
                context(
                    concat!("number (", stringify!($type_name), ")"),
                    map($implementation, $further_processing),
                )(s)
            }
        }
    };
}

macro_rules! unsigned_int {
    ($t:ident) => {
        number_impl! { $t { recognize(digit1) } }
    };
}

unsigned_int!(u8);
unsigned_int!(u16);
unsigned_int!(u32);
unsigned_int!(u64);

macro_rules! signed_int {
    ($t:ident) => {
        number_impl! { $t { recognize(tuple((opt(char('-')), digit1))) } }
    };
}

signed_int!(i8);
signed_int!(i16);
signed_int!(i32);
signed_int!(i64);

macro_rules! float {
    ($t:ident) => {
        number_impl! { $t { recognize_float } }
        number_impl! {
            NotNan<$t> {
                <$t>::from_sql
            } {
                |float| NotNan::new(float).expect("non-NaN")
            }
        }
    };
}

float!(f32);
float!(f64);

/// Use this for string-like types that have no escape sequences,
/// like timestamps, which only contain `[0-9: -]`.
impl<'a> FromSql<'a> for &'a str {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        context(
            "string with no escape sequences",
            map(
                preceded(
                    tag(B("'")),
                    terminated(
                        map(opt(is_not(B("'"))), |opt| {
                            opt.unwrap_or_else(|| B(""))
                        }),
                        tag(B("'")),
                    ),
                ),
                |bytes| {
                    std::str::from_utf8(bytes)
                        .expect("valid UTF-8 in unescaped string")
                },
            ),
        )(s)
    }
}

/// Use this for string types that require unescaping and are guaranteed
/// to be valid UTF-8, like page titles.
impl<'a> FromSql<'a> for String {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        context(
            "string",
            map(<Vec<u8>>::from_sql, |s| {
                String::from_utf8(s)
                    .expect("valid UTF-8 in potentially escaped string")
            }),
        )(s)
    }
}

/// This is used for "strings" that sometimes contain invalid UTF-8, like the
/// `cl_sortkey` field in the `categorylinks` table, which is truncated to 230
// bits, sometimes in the middle of a UTF-8 sequence.
impl<'a> FromSql<'a> for Vec<u8> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        context(
            "byte string",
            preceded(
                tag(B("'")),
                terminated(
                    map(
                        opt(escaped_transform(
                            is_not(B("\\\"'\r\n\t")),
                            '\\',
                            |s: &[u8]| {
                                map(one_of(B(r#"tnr\'""#)), |b| match b {
                                    't' => B("\t"),
                                    'n' => b"\n",
                                    'r' => b"\r",
                                    '\\' => b"\\",
                                    '\'' => b"'",
                                    '"' => b"\"",
                                    _ => unreachable!(),
                                })(s)
                            },
                        )),
                        |opt| opt.unwrap_or_else(Vec::new),
                    ),
                    tag(B("'")),
                ),
            ),
        )(s)
    }
}

impl<'a> FromSql<'a> for () {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        context("unit type", map(tag("NULL"), |_| ()))(s)
    }
}

impl<'a, T> FromSql<'a> for Option<T>
where
    T: FromSql<'a>,
{
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        context(
            "optional type",
            alt((
                context("“NULL”", map(<()>::from_sql, |_| None)),
                map(T::from_sql, Some),
            )),
        )(s)
    }
}

macro_rules! impl_wrapper {
    // $l1 and $l2 must be identical.
    (
        $(#[$attrib:meta])*
        $wrapper:ident<$l1:lifetime>: &$l2:lifetime $wrapped_type:ty
    ) => {
        impl_wrapper! {
            @maybe_copy [&$l2 $wrapped_type]
            $(#[$attrib])*
            pub struct $wrapper<$l1>(&$l2 $wrapped_type);

            impl<$l1> FromSql<$l1> for $wrapper<$l1> {
                fn from_sql(s: &$l1 [u8]) -> IResult<$l1, Self> {
                    context(
                        stringify!($wrapper),
                        map(<&$l2 $wrapped_type>::from_sql, $wrapper)
                    )(s)
                }
            }

            #[allow(unused)]
            impl<$l1> $wrapper<$l1> {
                pub fn into_inner(self) -> &$l2 $wrapped_type {
                    self.into()
                }
            }

            impl<$l1> From<$wrapper<$l1>> for &$l2 $wrapped_type {
                fn from(val: $wrapper<$l1>) -> Self {
                    val.0
                }
            }

            impl<$l1> From<&$l2 $wrapped_type> for $wrapper<$l1> {
                fn from(val: &$l2 $wrapped_type) -> Self {
                    Self(val)
                }
            }
        }
    };
    (
        $(#[$attrib:meta])*
        $wrapper:ident: $wrapped:ident
    ) => {
        impl_wrapper! {
            @maybe_copy [$wrapped]
            $(#[$attrib])*
            pub struct $wrapper($wrapped);

            impl<'input> FromSql<'input> for $wrapper {
                fn from_sql(s: &'input [u8]) -> IResult<'input, Self> {
                    context(
                        stringify!($wrapper),
                        map(<$wrapped>::from_sql, $wrapper)
                    )(s)
                }
            }

            #[allow(unused)]
            impl $wrapper {
                pub fn into_inner(self) -> $wrapped {
                    self.into()
                }
            }

            impl From<$wrapper> for $wrapped {
                fn from(val: $wrapper) -> Self {
                    val.0
                }
            }

            impl<'a> From<&'a $wrapper> for &'a $wrapped {
                fn from(val: &'a $wrapper) -> Self {
                    &val.0
                }
            }

            impl From<$wrapped> for $wrapper {
                fn from(val: $wrapped) -> Self {
                    Self(val)
                }
            }
        }
    };
    (
        @maybe_copy [$(u32)? $(i32)? $(&$l:lifetime $t:ty)?]
        $($rest:item)+
    ) => {
        #[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
        $($rest)+
    };
    (
        @maybe_copy [$($anything:tt)?]
        $($rest:item)+
    ) => {
        #[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
        $($rest)+
    };
}

impl_wrapper! {
    #[doc = "
Represents
[`page_id`](https://www.mediawiki.org/wiki/Manual:Page_table#page_id),
the primary key of the `page` table, as well as other fields in
other tables that correspond to it.
"]
    PageId: u32
}

impl_wrapper! {
    #[doc = "
Represents the
[`page_namespace`](https://www.mediawiki.org/wiki/Manual:Page_table#page_namespace)
field of the `page` table.
"]
    PageNamespace: i32
}

impl_wrapper! {
    #[doc="
Represents the
[`page_title`](https://www.mediawiki.org/wiki/Manual:Page_table#page_title)
field of the `page` table, a title with underscores.
"]
    PageTitle: String
}

impl_wrapper! {
    #[doc="
Represents a page title with namespace and with spaces rather than underscores,
as in the
[`ll_title`](https://www.mediawiki.org/wiki/Manual:Langlinks_table#ll_title)
field of the `langlinks` table.
"]
    FullPageTitle: String
}

impl_wrapper! {
    #[doc = "
Represents
[`cat_id`](https://www.mediawiki.org/wiki/Manual:Category_table#cat_id),
the primary key of the `category` table.
"]
    CategoryId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`log_id`](https://www.mediawiki.org/wiki/Manual:Logging_table#log_id),
the primary key of the `logging` table.
"]
    LogId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`ct_id`](https://www.mediawiki.org/wiki/Manual:Change_tag_table#ct_id),
the primary key of the `change_tag` table.
"]
    ChangeTagId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`rev_id`](https://www.mediawiki.org/wiki/Manual:Revision_table#rev_id),
the primary key of the `revision` table.
"]
    RevisionId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`ctd_id`](https://www.mediawiki.org/wiki/Manual:Change_tag_def_table#ctd_id),
the primary key of the `change_tag_def` table.
"]
    ChangeTagDefId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`rc_id`](https://www.mediawiki.org/wiki/Manual:Recentchanges_table#rc_id),
the primary key of the `recentchanges` table.
"]
    RecentChangesId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`el_id`](https://www.mediawiki.org/wiki/Manual:Externallinks_table#el_id),
the primary key of the `externallinks` table.
"]
    ExternalLinksId: u32
}

impl_wrapper! {
    #[doc = "
Represents the
[`img_minor_mime`](https://www.mediawiki.org/wiki/Manual:Image_table#img_minor_mime)
field of the `image` table.
"]
    MinorMime<'a>: &'a str
}

impl_wrapper! {
    #[doc = "
Represents
[`comment_id`](https://www.mediawiki.org/wiki/Manual:Comment_table#comment_id),
the primary key of the `comment` table.
"]
    CommentId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`actor_id`](https://www.mediawiki.org/wiki/Manual:Actor_table#actor_id),
the primary key of the `actor` table.
"]
    ActorId: u32
}

impl_wrapper! {
    #[doc = "
Represents a SHA-1 hash in base 36, for instance in the
[`img_sha1`](https://www.mediawiki.org/wiki/Manual:Image_table#img_sha1)
field of the `image` table.
"]
    Sha1<'a>: &'a str
}

impl_wrapper! {
    #[doc = "
Represents
[`pr_id`](https://www.mediawiki.org/wiki/Manual:Page_restrictions_table#pr_id),
the primary key of the `page_restrictions` table.
"]
    PageRestrictionsId: u32
}

impl_wrapper! {
    #[doc = "
Represents
[`user_id`](https://www.mediawiki.org/wiki/Manual:User_table#user_id),
the primary key of the `user` table.
"]
    UserId: u32
}

impl_wrapper! {
    #[doc = "
Represents the name of a user group, such as the
[`ug_group`](https://www.mediawiki.org/wiki/Manual:User_groups_table#ug_group)
field of the `user_groups` table.
"]
    UserGroup<'a>: &'a str
}

#[test]
fn test_copy_for_wrappers() {
    use static_assertions::*;
    assert_impl_all!(PageId: Copy);
    assert_not_impl_all!(PageTitle: Copy);
    assert_impl_all!(PageNamespace: Copy);
    assert_impl_all!(UserGroup: Copy);
}

/// Represents a [timestamp](https://www.mediawiki.org/wiki/Manual:Timestamp)
/// given as a string in `yyyymmddhhmmss` format. Provides the methods of
/// [`NaiveDateTime`] through
/// [`Deref`].
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct Timestamp(NaiveDateTime);

impl<'input> FromSql<'input> for Timestamp {
    fn from_sql(s: &'input [u8]) -> IResult<'input, Self> {
        context(
            "date and time in yyyymmddhhmmss or yyyy-mm-dd hh:mm::ss format",
            map_res(<&str>::from_sql, |s| {
                if s.len() == 14 {
                    NaiveDateTime::parse_from_str(s, "%Y%m%d%H%M%S")
                } else {
                    NaiveDateTime::parse_from_str(s, "%Y-%m-%d %H:%M:%S")
                }
                .map(Timestamp)
            }),
        )(s)
    }
}

impl Deref for Timestamp {
    type Target = NaiveDateTime;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

/// Represents the
/// [`pr_expiry`](https://www.mediawiki.org/wiki/Manual:Page_restrictions_table#pr_expiry)
/// field of the `page_restrictions` table.
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum Expiry {
    Timestamp(Timestamp),
    Infinity,
}

impl<'input> FromSql<'input> for Expiry {
    fn from_sql(s: &'input [u8]) -> IResult<'input, Self> {
        context(
            "expiry",
            alt((
                map(Timestamp::from_sql, Expiry::Timestamp),
                context(
                    "“infinity”",
                    map(tag("infinity"), |_| Expiry::Infinity),
                ),
            )),
        )(s)
    }
}

/// Represents the
/// [`cl_type`](https://www.mediawiki.org/wiki/Manual:Categorylinks_table#cl_type)
/// field of the `categorylinks` table.
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum PageType<'a> {
    Page,
    Subcat,
    File,
    Other(&'a str),
}

impl<'a> From<&'a str> for PageType<'a> {
    fn from(s: &'a str) -> Self {
        use PageType::*;
        match s {
            "page" => Page,
            "subcat" => Subcat,
            "file" => File,
            _ => Other(s),
        }
    }
}

impl<'a> FromSql<'a> for PageType<'a> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        map(<&str>::from_sql, PageType::from)(s)
    }
}

/// Represents the
/// [`pr_type`](https://www.mediawiki.org/wiki/Manual:Page_restrictions_table#pr_type)
/// field of the `page_restrictions` table, the action that is restricted.
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum PageAction<'a> {
    Edit,
    Move,
    Upload,
    All,
    Other(&'a str),
}

impl<'a> From<&'a str> for PageAction<'a> {
    fn from(s: &'a str) -> Self {
        use PageAction::*;
        match s {
            "edit" => Edit,
            "move" => Move,
            "upload" => Upload,
            _ => Other(s),
        }
    }
}

impl<'a> FromSql<'a> for PageAction<'a> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        map(<&str>::from_sql, PageAction::from)(s)
    }
}

/// Represents the
/// [`pr_level`](https://www.mediawiki.org/wiki/Manual:Page_restrictions_table#pr_level)
/// field of the `page_restrictions` table, the group that is allowed
/// to perform the action.
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum ProtectionLevel<'a> {
    Autoconfirmed,
    ExtendedConfirmed,
    Sysop,
    TemplateEditor,
    EditProtected,
    EditSemiProtected,
    /// The result of parsing the empty string after the `=` in `'move=:edit='`.
    None,
    Other(&'a str),
}

impl<'a> From<&'a str> for ProtectionLevel<'a> {
    fn from(s: &'a str) -> Self {
        use ProtectionLevel::*;
        match s {
            "autoconfirmed" => Autoconfirmed,
            "extendedconfirmed" => ExtendedConfirmed,
            "templateeditor" => TemplateEditor,
            "sysop" => Sysop,
            "editprotected" => EditProtected,
            "editsemiprotected" => EditSemiProtected,
            "" => None,
            _ => Other(s),
        }
    }
}

impl<'a> FromSql<'a> for ProtectionLevel<'a> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        map(<&str>::from_sql, ProtectionLevel::from)(s)
    }
}

/**
Represents [`page_restrictions`](https://www.mediawiki.org/wiki/Manual:Page_table#page_restrictions),
an outdated field of the `page` table containing a string representing
a map from action to the groups that are allowed to perform that action.

Here the action is represented by [`PageAction`]
and the protection level by [`ProtectionLevel`].
This field was replaced by the
[`page_restrictions` table](https://www.mediawiki.org/wiki/Manual:Page_restrictions_table)
in MediaWiki 1.10, but is still used by the software if a page's restrictions have not
been changed since MediaWiki 1.10 came out.

The string is in the following format, at least on the English Wiktionary:
```txt
# level on its own seems to be shorthand for both "edit" and "move"
"" | level | spec (":" spec)*
spec: action "=" level
# "" means no restrictions
level: "autoconfirmed" | "templateeditor" | "sysop" | ""
action: "edit" | "move" | "upload"
```
However, `spec` is treated as having the following format, because the
MediaWiki documentation for the `page` table
[gives](https://www.mediawiki.org/wiki/Manual:Page_table#page_restrictions)
the example `edit=autoconfirmed,sysop:move=sysop` with multiple protection
levels per action:

`spec`: `action "=" level ("," level)*`

The example given is nonsensical because `autoconfirmed` is a subset of
`sysop`, and neither English Wikipedia nor English Wiktionary have any
`page_restrictions` strings in this format, but perhaps another wiki does.
*/
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct PageRestrictionsOld<'a>(
    BTreeMap<PageAction<'a>, Vec<ProtectionLevel<'a>>>,
);

impl<'a> PageRestrictionsOld<'a> {
    pub fn len(&self) -> usize {
        self.0.len()
    }

    pub fn is_empty(&self) -> bool {
        self.len() == 0
    }

    pub fn iter(
        &self,
    ) -> impl Iterator<Item = (&PageAction<'a>, &Vec<ProtectionLevel<'a>>)>
    {
        self.0.iter()
    }
}

impl<'a> Index<PageAction<'a>> for PageRestrictionsOld<'a> {
    type Output = Vec<ProtectionLevel<'a>>;

    fn index(&self, idx: PageAction<'a>) -> &Self::Output {
        &self.0[&idx]
    }
}

impl<'a> FromIterator<(PageAction<'a>, Vec<ProtectionLevel<'a>>)>
    for PageRestrictionsOld<'a>
{
    fn from_iter<
        I: IntoIterator<Item = (PageAction<'a>, Vec<ProtectionLevel<'a>>)>,
    >(
        iter: I,
    ) -> Self {
        PageRestrictionsOld(iter.into_iter().collect())
    }
}

impl<'a> FromSql<'a> for PageRestrictionsOld<'a> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        map(<&str>::from_sql, |contents| {
            PageRestrictionsOld(
                contents
                    .split(':')
                    .filter(|p| !p.is_empty())
                    .map(|restriction| {
                        let mut type_and_levels = restriction.rsplitn(2, '=');
                        let level = type_and_levels
                            .next()
                            .expect("level of page restriction")
                            .split(',')
                            .map(|l| l.into())
                            .collect();
                        let action = type_and_levels
                            .next()
                            .map(|a| a.into())
                            .unwrap_or(PageAction::All);
                        (action, level)
                    })
                    .collect(),
            )
        })(s)
    }
}

#[test]
fn test_page_restrictions() {
    use PageAction::*;
    use ProtectionLevel::*;
    assert_eq!(
        PageRestrictionsOld::from_sql(B("'edit=autoconfirmed:move=sysop'")),
        Ok((
            B(""),
            vec![(Edit, vec![Autoconfirmed]), (Move, vec![Sysop])]
                .into_iter()
                .collect()
        )),
    );
    assert_eq!(
        PageRestrictionsOld::from_sql(B("''")),
        Ok((B(""), PageRestrictionsOld(BTreeMap::new()))),
    );
    assert_eq!(
        PageRestrictionsOld::from_sql(B("'sysop'")),
        Ok((B(""), vec![(All, vec![Sysop])].into_iter().collect())),
    );
    assert_eq!(
        PageRestrictionsOld::from_sql(B("'move=:edit='")),
        Ok((
            B(""),
            vec![(Move, vec![None]), (Edit, vec![None])]
                .into_iter()
                .collect()
        )),
    );
}

/// Represents the
/// [`page_content_model`](https://www.mediawiki.org/wiki/Manual:Page_table#page_content_model)
/// field of the `page` table.
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum ContentModel<'a> {
    Wikitext,
    Scribunto,
    Text,
    CSS,
    SanitizedCSS,
    JavaScript,
    JSON,
    Other(&'a str),
}

impl<'a> From<&'a str> for ContentModel<'a> {
    fn from(s: &'a str) -> Self {
        use ContentModel::*;
        match s {
            "wikitext" => Wikitext,
            "Scribunto" => Scribunto,
            "text" => Text,
            "css" => CSS,
            "sanitized-css" => SanitizedCSS,
            "javascript" => JavaScript,
            "json" => JSON,
            _ => Other(s),
        }
    }
}

impl<'a> FromSql<'a> for ContentModel<'a> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        map(<&str>::from_sql, ContentModel::from)(s)
    }
}

/// Represents the
/// [`img_media_type`](https://www.mediawiki.org/wiki/Manual:Image_table#img_media_type)
/// field of the `image` table.
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum MediaType<'a> {
    Unknown,
    Bitmap,
    Drawing,
    Audio,
    Video,
    Multimedia,
    Office,
    Text,
    Executable,
    Archive,
    /// Unfortunately a variant name cannot begin with a number.
    ThreeD,
    Other(&'a str),
}

impl<'a> From<&'a str> for MediaType<'a> {
    fn from(s: &'a str) -> Self {
        use MediaType::*;
        match s {
            "UNKNOWN" => Unknown,
            "BITMAP" => Bitmap,
            "DRAWING" => Drawing,
            "AUDIO" => Audio,
            "VIDEO" => Video,
            "MULTIMEDIA" => Multimedia,
            "OFFICE" => Office,
            "TEXT" => Text,
            "EXECUTABLE" => Executable,
            "ARCHIVE" => Archive,
            "3D" => ThreeD,
            _ => Other(s),
        }
    }
}

impl<'a> FromSql<'a> for MediaType<'a> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        map(<&str>::from_sql, MediaType::from)(s)
    }
}

/// Represents the
/// [`img_major_mime`](https://www.mediawiki.org/wiki/Manual:Image_table#img_major_mime)
/// field of the `image` table.
#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum MajorMime<'a> {
    Unknown,
    Application,
    Audio,
    Image,
    Text,
    Video,
    Message,
    Model,
    Multipart,
    Other(&'a str),
}

impl<'a> From<&'a str> for MajorMime<'a> {
    fn from(s: &'a str) -> Self {
        use MajorMime::*;
        match s {
            "unknown" => Unknown,
            "application" => Application,
            "audio" => Audio,
            "image" => Image,
            "text" => Text,
            "video" => Video,
            "message" => Message,
            "model" => Model,
            "multipart" => Multipart,
            _ => Other(s),
        }
    }
}

impl<'a> FromSql<'a> for MajorMime<'a> {
    fn from_sql(s: &'a [u8]) -> IResult<'a, Self> {
        map(<&str>::from_sql, MajorMime::from)(s)
    }
}

#[test]
fn test_bool() {
    for (s, v) in &[(B("0"), false), (B("1"), true)] {
        assert_eq!(bool::from_sql(s), Ok((B(""), *v)));
    }
}

#[test]
fn test_numbers() {
    fn from_utf8(s: &[u8]) -> &str {
        std::str::from_utf8(s).unwrap()
    }

    // Add a space to the end to avoid `nom::Err::Incomplete`.
    let f = B("0.37569 ");
    let res = f64::from_sql(f);
    assert_eq!(res, Ok((B(" "), from_utf8(f).trim_end().parse().unwrap())));

    for i in &[B("1 "), B("-1 ")] {
        assert_eq!(
            i32::from_sql(i),
            Ok((B(" "), from_utf8(i).trim_end().parse().unwrap()))
        );
    }
}

#[test]
fn test_string() {
    let strings = &[
        (B(r"'\''"), r"'"),
        (br"'\\'", r"\"),
        (br"'\n'", "\n"),
        (br"'string'", r"string"),
        (
            br#"'English_words_ending_in_\"-vorous\",_\"-phagous\"_and_similar_endings'"#,
            r#"English_words_ending_in_"-vorous",_"-phagous"_and_similar_endings"#,
        ),
    ];
    for (s, unescaped) in strings {
        assert_eq!(String::from_sql(s), Ok((B(""), (*unescaped).to_string())));
    }
}