//! # Substrate Enterprise Sample - Product Registry example pallet

#![cfg_attr(not(feature = "std"), no_std)]

use codec::{Decode, Encode};
use core::result::Result;
use frame_support::{
    decl_error, decl_event, decl_module, decl_storage, dispatch, ensure, sp_runtime::RuntimeDebug,
    sp_std::prelude::*, traits::EnsureOrigin,
};
use frame_system::{self as system, ensure_signed};

#[cfg(test)]
mod mock;

#[cfg(test)]
mod tests;

// General constraints to limit data size
// Note: these could also be passed as trait config parameters
pub const PRODUCT_ID_MAX_LENGTH: usize = 14;
pub const PRODUCT_PROP_NAME_MAX_LENGTH: usize = 10;
pub const PRODUCT_PROP_VALUE_MAX_LENGTH: usize = 20;
pub const PRODUCT_MAX_PROPS: usize = 3;

// Custom types
pub type ProductId = Vec<u8>;
pub type PropName = Vec<u8>;
pub type PropValue = Vec<u8>;

// Product contains master data (aka class-level) about a trade item.
// This data is typically registered once by the product's manufacturer / supplier,
// to be shared with other network participants, and remains largely static.
// It can also be used for instance-level (lot) master data.
#[derive(Encode, Decode, Clone, PartialEq, Eq, RuntimeDebug)]
pub struct Product<AccountId, Moment> {
    // The product ID would typically be a GS1 GTIN (Global Trade Item Number),
    // or ASIN (Amazon Standard Identification Number), or similar,
    // a numeric or alpha-numeric code with a well-defined data structure.
    id: ProductId,
    // This is account that represents the owner of this product, as in
    // the manufacturer or supplier providing this product within the value chain.
    owner: AccountId,
    // This a series of properties describing the product.
    // Typically, there would at least be a textual description, and SKU.
    // It could also contain instance / lot master data e.g. expiration, weight, harvest date.
    props: Option<Vec<ProductProperty>>,
    // Timestamp (approximate) at which the prodct was registered on-chain.
    registered: Moment,
}

// Contains a name-value pair for a product property e.g. description: Ingredient ABC
#[derive(Encode, Decode, Clone, PartialEq, Eq, RuntimeDebug)]
pub struct ProductProperty {
    // Name of the product property e.g. desc or description
    name: PropName,
    // Value of the product property e.g. Ingredient ABC
    value: PropValue,
}

impl ProductProperty {
    pub fn new(name: &[u8], value: &[u8]) -> Self {
        Self {
            name: name.to_vec(),
            value: value.to_vec(),
        }
    }

    pub fn name(&self) -> &[u8] {
        self.name.as_ref()
    }

    pub fn value(&self) -> &[u8] {
        self.value.as_ref()
    }
}

pub trait Trait: system::Trait + timestamp::Trait {
    type Event: From<Event<Self>> + Into<<Self as system::Trait>::Event>;
    type CreateRoleOrigin: EnsureOrigin<Self::Origin>;
}

decl_storage! {
    trait Store for Module<T: Trait> as ProductRegistry {
        pub Products get(fn product_by_id): map hasher(blake2_128_concat) ProductId => Option<Product<T::AccountId, T::Moment>>;
        pub ProductsOfOrganization get(fn products_of_org): map hasher(blake2_128_concat) T::AccountId => Vec<ProductId>;
        pub OwnerOf get(fn owner_of): map hasher(blake2_128_concat) ProductId => Option<T::AccountId>;
    }
}

decl_event!(
    pub enum Event<T>
    where
        AccountId = <T as system::Trait>::AccountId,
    {
        ProductRegistered(AccountId, ProductId, AccountId),
    }
);

decl_error! {
    pub enum Error for Module<T: Trait> {
        ProductIdMissing,
        ProductIdTooLong,
        ProductIdExists,
        ProductTooManyProps,
        ProductInvalidPropName,
        ProductInvalidPropValue
    }
}

decl_module! {
    pub struct Module<T: Trait> for enum Call where origin: T::Origin {
        type Error = Error<T>;
        fn deposit_event() = default;

        #[weight = 10_000]
        pub fn register_product(origin, id: ProductId, owner: T::AccountId, props: Option<Vec<ProductProperty>>) -> dispatch::DispatchResult {
            T::CreateRoleOrigin::ensure_origin(origin.clone())?;
            let who = ensure_signed(origin)?;

            // Validate product ID
            Self::validate_product_id(&id)?;

            // Validate product props
            Self::validate_product_props(&props)?;

            // Check product doesn't exist yet (1 DB read)
            Self::validate_new_product(&id)?;

            // TODO: if organization has an attribute w/ GS1 Company prefix,
            //       additional validation could be applied to the product ID
            //       to ensure its validity (same company prefix as org).

            // Create a product instance
            let product = Self::new_product()
                .identified_by(id.clone())
                .owned_by(owner.clone())
                .registered_on(<timestamp::Module<T>>::now())
                .with_props(props)
                .build();

            // Add product & ownerOf (3 DB writes)
            <Products<T>>::insert(&id, product);
            <ProductsOfOrganization<T>>::append(&owner, &id);
            <OwnerOf<T>>::insert(&id, &owner);

            Self::deposit_event(RawEvent::ProductRegistered(who, id, owner));

            Ok(())
        }
    }
}

impl<T: Trait> Module<T> {
    // Helper methods
    fn new_product() -> ProductBuilder<T::AccountId, T::Moment> {
        ProductBuilder::<T::AccountId, T::Moment>::default()
    }

    pub fn validate_product_id(id: &[u8]) -> Result<(), Error<T>> {
        // Basic product ID validation
        ensure!(!id.is_empty(), Error::<T>::ProductIdMissing);
        ensure!(
            id.len() <= PRODUCT_ID_MAX_LENGTH,
            Error::<T>::ProductIdTooLong
        );
        Ok(())
    }

    pub fn validate_new_product(id: &[u8]) -> Result<(), Error<T>> {
        // Product existence check
        ensure!(
            !<Products<T>>::contains_key(id),
            Error::<T>::ProductIdExists
        );
        Ok(())
    }

    pub fn validate_product_props(props: &Option<Vec<ProductProperty>>) -> Result<(), Error<T>> {
        if let Some(props) = props {
            ensure!(
                props.len() <= PRODUCT_MAX_PROPS,
                Error::<T>::ProductTooManyProps,
            );
            for prop in props {
                ensure!(
                    prop.name().len() <= PRODUCT_PROP_NAME_MAX_LENGTH,
                    Error::<T>::ProductInvalidPropName
                );
                ensure!(
                    prop.value().len() <= PRODUCT_PROP_VALUE_MAX_LENGTH,
                    Error::<T>::ProductInvalidPropValue
                );
            }
        }
        Ok(())
    }
}

#[derive(Default)]
pub struct ProductBuilder<AccountId, Moment>
where
    AccountId: Default,
    Moment: Default,
{
    id: ProductId,
    owner: AccountId,
    props: Option<Vec<ProductProperty>>,
    registered: Moment,
}

impl<AccountId, Moment> ProductBuilder<AccountId, Moment>
where
    AccountId: Default,
    Moment: Default,
{
    pub fn identified_by(mut self, id: ProductId) -> Self {
        self.id = id;
        self
    }

    pub fn owned_by(mut self, owner: AccountId) -> Self {
        self.owner = owner;
        self
    }

    pub fn with_props(mut self, props: Option<Vec<ProductProperty>>) -> Self {
        self.props = props;
        self
    }

    pub fn registered_on(mut self, registered: Moment) -> Self {
        self.registered = registered;
        self
    }

    pub fn build(self) -> Product<AccountId, Moment> {
        Product::<AccountId, Moment> {
            id: self.id,
            owner: self.owner,
            props: self.props,
            registered: self.registered,
        }
    }
}