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// Copyright 2019-2025 Parity Technologies (UK) Ltd.
// This file is dual-licensed as Apache-2.0 or GPL-3.0.
// see LICENSE for license details.
//! # Blocks
//!
//! The [blocks API](crate::blocks::BlocksClient) in Subxt unifies many of the other interfaces, and
//! allows you to:
//!
//! - Access information about specific blocks (see [`crate::blocks::BlocksClient::at()`] and
//! [`crate::blocks::BlocksClient::at_latest()`]).
//! - Subscribe to [all](crate::blocks::BlocksClient::subscribe_all()),
//! [best](crate::blocks::BlocksClient::subscribe_best()) or
//! [finalized](crate::blocks::BlocksClient::subscribe_finalized()) blocks as they are produced.
//! **Prefer to subscribe to finalized blocks unless you know what you're doing.**
//!
//! In either case, you'll end up with [`crate::blocks::Block`]'s, from which you can access various
//! information about the block, such a the [header](crate::blocks::Block::header()),
//! [block number](crate::blocks::Block::number()) and [body (the
//! extrinsics)](crate::blocks::Block::extrinsics()). [`crate::blocks::Block`]'s also provide
//! shortcuts to other Subxt APIs that will operate at the given block:
//!
//! - [storage](crate::blocks::Block::storage()),
//! - [events](crate::blocks::Block::events())
//! - [runtime APIs](crate::blocks::Block::runtime_api())
//!
//! Aside from these links to other Subxt APIs, the main thing that we can do here is iterate over
//! and decode the extrinsics in a block body.
//!
//! ## Decoding Extrinsics
//!
//! Given a block, you can [download the block body](crate::blocks::Block::extrinsics()) and
//! [iterate over the extrinsics](crate::blocks::Extrinsics::iter) stored within it. The extrinsics
//! yielded are of type [ExtrinsicDetails](crate::blocks::ExtrinsicDetails), which is just a blob of
//! bytes that also stores which pallet and call in that pallet it belongs to. It also contains
//! information about signed extensions that have been used for submitting this extrinsic.
//!
//! To use the extrinsic, you probably want to decode it into a concrete Rust type. These Rust types
//! representing extrinsics from different pallets can be generated from metadata using the subxt
//! macro or the CLI tool.
//!
//! When decoding the extrinsic into a static type you have two options:
//!
//! ### Statically decode the extrinsics into [the root extrinsic type](crate::blocks::ExtrinsicDetails::as_root_extrinsic())
//!
//! The root extrinsic type generated by subxt is a Rust enum with one variant for each pallet. Each
//! of these variants has a field that is another enum whose variants cover all calls of the
//! respective pallet. If the extrinsic bytes are valid and your metadata matches the chain's
//! metadata, decoding the bytes of an extrinsic into this root extrinsic type should always
//! succeed.
//!
//! This example shows how to subscribe to blocks and decode the extrinsics in each block into the
//! root extrinsic type. Once we get hold of the
//! [ExtrinsicDetails](crate::blocks::ExtrinsicDetails), we can decode it statically or dynamically.
//! We can also access details about the extrinsic, including the associated events and transaction
//! extensions.
//!
//! ```rust,ignore
//! ```
//!
//! ### Statically decode the extrinsic into [a specific pallet call](crate::blocks::ExtrinsicDetails::as_extrinsic())
//!
//! This is useful if you are expecting a specific extrinsic to be part of some block. If the extrinsic you try to decode
//! is a different extrinsic, an `Ok(None)` value is returned from [`as_extrinsic::<T>()`](crate::blocks::ExtrinsicDetails::as_extrinsic());
//!
//! If you are only interested in finding specific extrinsics in a block, you can also [iterate over all of them](crate::blocks::Extrinsics::find),
//! get only [the first one](crate::blocks::Extrinsics::find_first), or [the last one](crate::blocks::Extrinsics::find_last).
//!
//! The following example monitors `TransferKeepAlive` extrinsics on the Pezkuwi network.
//! We statically decode them and access the [tip](crate::blocks::ExtrinsicTransactionExtensions::tip()) and
//! [account nonce](crate::blocks::ExtrinsicTransactionExtensions::nonce()) transaction extensions.
//! ```rust,ignore
//! ```
//!
//! ### Dynamically decode the extrinsic
//!
//! Sometimes you might use subxt with metadata that is not known at compile time. In this case, you do not
//! have access to a statically generated interface module that contains the relevant Rust types. You can
//! [decode ExtrinsicDetails dynamically](crate::blocks::ExtrinsicDetails::decode_as_fields()), which gives
//! you access to it's fields as a [scale value composite](scale_value::Composite). The following example
//! looks for signed extrinsics on the Pezkuwi network and retrieves their pallet name, variant name, data
//! fields and transaction extensions dynamically. Notice how we do not need to use code generation via the
//! subxt macro. The only fixed component we provide is the [PezkuwiConfig](crate::config::PezkuwiConfig).
//! Other than that it works in a chain-agnostic way:
//! ```rust,ignore
//! ```
//!
//! ## Decoding transaction extensions
//!
//! Extrinsics can contain transaction extensions. The transaction extensions can be different across chains.
//! The [Config](crate::Config) implementation for your chain defines which transaction extensions you expect.
//! Once you get hold of the [ExtrinsicDetails](crate::blocks::ExtrinsicDetails) for an extrinsic you are interested in,
//! you can try to [get its transaction extensions](crate::blocks::ExtrinsicDetails::transaction_extensions()).
//! These are only available on V4 signed extrinsics or V5 general extrinsics. You can try to
//! [find a specific transaction extension](crate::blocks::ExtrinsicTransactionExtensions::find), in the returned
//! [transaction extensions](crate::blocks::ExtrinsicTransactionExtensions).
//!
//! Subxt also provides utility functions to get the [tip](crate::blocks::ExtrinsicTransactionExtensions::tip()) and
//! the [account nonce](crate::blocks::ExtrinsicTransactionExtensions::nonce()) associated with an extrinsic, given
//! its transaction extensions. If you prefer to do things dynamically you can get the data of the transaction extension
//! as a [scale value](crate::blocks::ExtrinsicTransactionExtension::value()).