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//! This file contains the macros used for creating validating entry type definitions,
//! and validating links definitions within those.

use crate::error::{ZomeApiError, ZomeApiResult};
use holochain_core_types::{
    agent::AgentId,
    dna::entry_types::EntryTypeDef,
    entry::{entry_type::EntryType, AppEntryValue, Entry},
    validation::{EntryValidationData, LinkValidationData, ValidationPackageDefinition},
};
use holochain_wasm_utils::api_serialization::validation::LinkDirection;
use std::convert::TryFrom;

pub type PackageCreator = Box<dyn FnMut() -> ValidationPackageDefinition + Sync>;

pub type Validator = Box<dyn FnMut(EntryValidationData<Entry>) -> Result<(), String> + Sync>;

pub type AgentValidator = Box<dyn FnMut(EntryValidationData<AgentId>) -> Result<(), String> + Sync>;
pub type LinkValidator = Box<dyn FnMut(LinkValidationData) -> Result<(), String> + Sync>;

/// This struct represents a complete entry type definition.
/// It wraps [EntryTypeDef](holochain_core_types::dna::entry_types::EntryTypeDef) defined in the DNA crate
/// which only represents the static parts that show up in the JSON definition
/// of an entry type.
/// What is missing from there is the validation callbacks that can not be defined as JSON
/// and are added here as Box<FnMut> objects (types PackageCreator, Validator, LinkValidator)
///
/// Instances of this struct are expected and used in the [define_zome! macro](define_zome!).
/// Although possible, a DNA developer does not need to create these instances directly but instead
/// should use the [entry! macro](entry!) for a clean syntax.
pub struct ValidatingEntryType {
    /// Name of the entry type
    pub name: EntryType,
    /// All the static aspects of the entry type as
    pub entry_type_definition: EntryTypeDef,
    /// Callback that returns a validation package definition that Holochain reads in order
    /// to create the right validation package to pass in to the validator callback on validation.
    pub package_creator: PackageCreator,
    /// This is the validation callback that is used to determine if an entry is valid.
    pub validator: Validator,

    pub links: Vec<ValidatingLinkDefinition>,
}

/// Similar to ValidatingEntryType, this provides the dynamic aspects of link definitions,
/// the validation callbacks, and thus completes the structs in the DNA crate.
/// The [entry! macro](entry!) expects an array of links that are represented by
/// instances of this struct.
///
/// DNA developers don't need to use this type directly but instead should use the
/// [link!](link!), [to!](to!) or [from!](from!) macro.
pub struct ValidatingLinkDefinition {
    /// Is this link defined as pointing from this entry type to some other type,
    /// or from the other type to this?
    pub direction: LinkDirection,
    /// The other entry type the link connects this entry type to
    pub other_entry_type: String,
    /// Tag (i.e. name) of this type of links
    pub link_type: String,
    /// Callback that returns a validation package definition that Holochain reads in order
    /// to create the right validation package to pass in to the validator callback on validation.
    pub package_creator: PackageCreator,
    /// This is the validation callback that is used to determine if a link is valid.
    pub validator: LinkValidator,
}

/// The `entry` macro is a helper for creating `ValidatingEntryType` definitions
/// for use within the [define_zome](define_zome!) macro.
/// It has 7 component parts:
/// 1. name: `name` is simply the descriptive name of the entry type, such as "post", or "user".
///      It is what must be given as the `entry_type_name` argument when calling [commit_entry](api::commit_entry()) and the other data read/write functions.
/// 2. description: `description` is something that is primarily for human readers of your code, just describe this entry type
/// 3. sharing: `sharing` defines what distribution over the DHT, or not, occurs with entries of this type, possible values
///      are defined in the [Sharing](holochain_core_types::dna::entry_types::Sharing) enum
/// 4. native_type: `native_type` references a given Rust struct, which provides a clear schema for entries of this type.
/// 5. validation_package: `validation_package` is a special identifier, which declares which data is required from peers
///      when attempting to validate entries of this type.
///      Possible values are found within [ValidationPackageDefinition](ValidationPackageDefinition)
/// 6. validation: `validation` is a callback function which will be called any time that a
///      (DHT) node processes or stores this entry, triggered through actions such as [commit_entry](api::commit_entry()), [update_entry](api::update_entry()), [remove_entry](api::remove_entry()).
///      It always expects two arguments, the first of which is the entry attempting to be validated,
///      the second is the validation `context`, which offers a variety of metadata useful for validation.
///      See [ValidationData](ValidationData) for more details.
/// 7. links: `links` is a vector of link definitions represented by `ValidatingLinkDefinition`.
///     Links can be defined with the `link!` macro or, more concise, with either the `to!` or `from!` macro,
///     to define an association pointing from this entry type to another, or one that points back from
///     the other entry type to this one.
///     See [link!](link!), [to!](to!) and [from!](from!) for more details.
/// # Examples
/// The following is a standalone Rust file that exports a function which can be called
/// to get a `ValidatingEntryType` of a "post".
/// ```rust
/// # extern crate boolinator;
/// # extern crate serde_json;
/// # #[macro_use]
/// # extern crate hdk;
/// # #[macro_use]
/// # extern crate holochain_json_derive;
/// # extern crate holochain_persistence_api;
/// # extern crate holochain_json_api;
/// # #[macro_use]
/// # extern crate serde_derive;
/// # use boolinator::*;
/// # use hdk::entry_definition::ValidatingEntryType;
/// # use holochain_persistence_api::{
/// #   cas::content::Address,
/// # };
/// # use holochain_json_api::{
/// #   json::JsonString,
/// #   error::JsonError,
/// # };
/// # use hdk::holochain_core_types::{
/// #   dna::entry_types::Sharing,
/// #   error::HolochainError,
/// #   validation::EntryValidationData
/// # };
///
/// # fn main() {
///
/// #[derive(Serialize, Deserialize, Debug, DefaultJson,Clone)]
/// pub struct Post {
///     content: String,
///     date_created: String,
/// }
///
/// pub fn definition() -> ValidatingEntryType {
///     entry!(
///         name: "post",
///         description: "a short social media style sharing of content",
///         sharing: Sharing::Public,
///
///         validation_package: || {
///             hdk::ValidationPackageDefinition::ChainFull
///         },
///
///         validation: |validation_data: hdk::EntryValidationData<Post>| {
///              match validation_data
///              {
///              EntryValidationData::Create{entry:test_entry,validation_data:_} =>
///              {
///
///
///                        (test_entry.content != "FAIL")
///                        .ok_or_else(|| "FAIL content is not allowed".to_string())
///                }
///                _ =>
///                 {
///                      Err("Failed to validate with wrong entry type".to_string())
///                }
///         }},
///
///         links: [
///             to!(
///                 "post",
///                 link_type: "comments",
///
///                 validation_package: || {
///                     hdk::ValidationPackageDefinition::ChainFull
///                 },
///
///                 validation: | _validation_data: hdk::LinkValidationData| {
///                     Ok(())
///                 }
///             )
///         ]
///     )
/// }
///
/// # }
/// ```

#[macro_export]
macro_rules! entry {
    (
        name: $name:expr,
        description: $properties:expr,
        sharing: $sharing:expr,
       // $(native_type: $native_type:ty,)*

        validation_package: || $package_creator:expr,
        validation: | $validation_data:ident : hdk::EntryValidationData<$native_type:ty> | $entry_validation:expr

        $(
            ,
            links : [
                $( $link_expr:expr ),*
            ]
        )*

    ) => (

        {
            let mut entry_type = $crate::holochain_core_types::dna::entry_types::EntryTypeDef::new();
            entry_type.properties = $crate::holochain_json_api::json::JsonString::from($properties);
            entry_type.sharing = $sharing;

            $($(
                match $link_expr.direction {
                    $crate::LinkDirection::To => {
                        entry_type.links_to.push(
                            $crate::holochain_core_types::dna::entry_types::LinksTo{
                                target_type: $link_expr.other_entry_type,
                                link_type: $link_expr.link_type,
                            }
                        );
                    },
                    $crate::LinkDirection::From => {
                        entry_type.linked_from.push(
                            $crate::holochain_core_types::dna::entry_types::LinkedFrom{
                                base_type: $link_expr.other_entry_type,
                                link_type: $link_expr.link_type,
                            }
                        );
                    }
                }

            )*)*

            let package_creator = Box::new(|| {
                $package_creator
            });

            let validator = Box::new(|validation_data: $crate::holochain_wasm_utils::holochain_core_types::validation::EntryValidationData<$crate::holochain_core_types::entry::Entry>| {
                let $validation_data = $crate::entry_definition::entry_to_native_type::<$native_type>(validation_data.clone())?;
                use std::convert::TryFrom;
                let e_type = $crate::holochain_core_types::entry::entry_type::EntryType::try_from(validation_data)?;
                match e_type {
                    $crate::holochain_core_types::entry::entry_type::EntryType::App(_) => {
                        $entry_validation
                    },
                    $crate::holochain_core_types::entry::entry_type::EntryType::Deletion =>
                    {
                        $entry_validation
                    }
                    _ => {
                        Err(String::from("Schema validation failed"))?
                    }
                }
            });

            $crate::entry_definition::ValidatingEntryType {
                name: $crate::holochain_core_types::entry::entry_type::EntryType::App($crate::holochain_core_types::entry::entry_type::AppEntryType::from($name.to_string())),
                entry_type_definition: entry_type,
                package_creator,
                validator,
                links: vec![
                    $($(
                        $link_expr
                    ),*)*
                ],
            }
        }
    );
}

/// The `link` macro is a helper for creating `ValidatingEntryType` definitions
/// for use within the [entry](entry!) macro.
/// It has 5 component parts:
/// 1. direction: `direction` defines if this entry type (in which the link is defined) points
///     to another entry, or if it is referenced from another entry.
///     The latter is needed in cases where the definition of the entry to link from is not
///     accessible because it is a system entry type (AGENT_ADDRESS), or the other entry is
///     defined in library zome.
///     Must be of type [LinkDirection](LinkDirection), so either `hdk::LinkDirection::To`
///     or `hdk::LinkDirection::From`.
/// 2. other_type: `other_type` is the entry type this link connects to. If direction is `to` this
///     would be the link target, if direction is `from` this defines the link's base type.
/// 3. link_type: `link_type` is the name of this association and thus the handle by which it can be retrieved
///     if given to [get_links()](api::get_links()) in conjunction with the base address.
/// 4. validation_package: Similar to entries, links have to be validated.
///        `validation_package` is a special identifier, which declares which data is required from peers
///         when attempting to validate entries of this type.
///         Possible values are found within [ValidationPackageDefinition](ValidationPackageDefinition)
/// 5. validation: `validation` is a callback function which will be called any time that a
///         (DHT) node processes or stores a link of this kind, triggered through the link actions [link_entries](api::commit_entry()) and [remove_link](api::remove_link()).
///         It always expects three arguments, the first being the base and the second the target of the link.
///         The third is the validation `context`, which offers a variety of metadata useful for validation.
///         See [ValidationData](ValidationData) for more details.
#[macro_export]
macro_rules! link {
    (
        direction: $direction:expr,
        other_type: $other_type:expr,
        link_type: $link_type:expr,

        validation_package: || $package_creator:expr,
        validation: | $validation_data:ident : hdk::LinkValidationData | $link_validation:expr
    ) => (

        {
            let package_creator = Box::new(|| {
                $package_creator
            });

            let validator = Box::new(|validation_data: $crate::holochain_wasm_utils::holochain_core_types::validation::LinkValidationData| {
                let $validation_data = validation_data;
                $link_validation
            });


            $crate::entry_definition::ValidatingLinkDefinition {
                direction: $direction,
                other_entry_type: String::from($other_type),
                link_type: String::from($link_type),
                package_creator,
                validator,
            }
        }
    );
}

/// The `to` macro is a helper for creating `ValidatingEntryType` definitions
/// for use within the [entry](entry!) macro.
/// It is a convenience wrapper around [link!](link!) that has all the
/// same properties except for the direction which gets set to `LinkDirection::To`.
#[macro_export]
macro_rules! to {
    (
        $other_type:expr,
        link_type: $link_type:expr,

        validation_package: || $package_creator:expr,
        validation: | $validation_data:ident : hdk::LinkValidationData | $link_validation:expr
    ) => (
        link!(
            direction: $crate::LinkDirection::To,
            other_type: $other_type,
            link_type: $link_type,

            validation_package: || $package_creator,
            validation: | $validation_data : hdk::LinkValidationData | $link_validation
        )
    )
}

/// The `from` macro is a helper for creating `ValidatingEntryType` definitions
/// for use within the [entry](entry!) macro.
/// It is a convenience wrapper around [link!](link!) that has all the
/// same properties except for the direction which gets set to `LinkDirection::From`.
#[macro_export]
macro_rules! from {
    (
        $other_type:expr,
        link_type: $link_type:expr,

        validation_package: || $package_creator:expr,
        validation: |  $validation_data:ident : hdk::LinkValidationData | $link_validation:expr
    ) => (
        link!(
            direction: $crate::LinkDirection::From,
            other_type: $other_type,
            link_type: $link_type,

            validation_package: || $package_creator,
            validation: |  $validation_data : hdk::LinkValidationData | $link_validation
        )
    )
}

//could not turn this to try_from
pub fn entry_to_native_type<T: TryFrom<AppEntryValue> + Clone>(
    entry_validation: EntryValidationData<Entry>,
) -> ZomeApiResult<EntryValidationData<T>> {
    match entry_validation {
        EntryValidationData::Create {
            entry,
            validation_data,
        } => {
            let native_type = convert_entry_validation_to_native::<T>(entry)?;
            Ok(EntryValidationData::Create {
                entry: native_type,
                validation_data,
            })
        }
        EntryValidationData::Modify {
            new_entry,
            old_entry,
            old_entry_header,
            validation_data,
        } => {
            let new_entry = convert_entry_validation_to_native::<T>(new_entry)?;
            let old_entry = convert_entry_validation_to_native::<T>(old_entry)?;
            Ok(EntryValidationData::Modify {
                new_entry,
                old_entry,
                old_entry_header,
                validation_data,
            })
        }
        EntryValidationData::Delete {
            old_entry,
            old_entry_header,
            validation_data,
        } => {
            let old_entry = convert_entry_validation_to_native::<T>(old_entry)?;
            Ok(EntryValidationData::Delete {
                old_entry,
                old_entry_header,
                validation_data,
            })
        }
    }
}

fn convert_entry_validation_to_native<T: TryFrom<AppEntryValue> + Clone>(
    entry: Entry,
) -> ZomeApiResult<T> {
    match entry {
        Entry::App(_, entry_value) => T::try_from(entry_value.to_owned()).map_err(|_| {
            ZomeApiError::Internal(
                vec![
                    "Could not convert Entry result to requested type : ".to_string(),
                    entry_value.to_string(),
                ]
                .join(&String::new()),
            )
        }),
        _ => Err(ZomeApiError::Internal(
            "Entry did not return an app entry".to_string(),
        )),
    }
}