extrinsics: Decode extrinsics from blocks (#929)

* Update polkadot.scale

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics: Add extrinsics client

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics: Decode extrinsics

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add extrinsic error

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* blocks: Expose extrinsics

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Fetch and decode block extrinsics

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Fix clippy

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics: Fetch pallet and variant index

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Move extrinsics on the subxt::blocks

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* example: Adjust example

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* metadata: Collect ExtrinsicMetadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Implement StaticExtrinsic for the calls

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Adjust examples

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Add root level Call enum

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Adjust testing

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add new decode interface

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Merge ExtrinsicError with BlockError

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Find first extrinsic

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Move code to extrinsic_types

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Add Extrinsic struct

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Adjust examples

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* test: Decode extinsics

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics/test: Add fake metadata for static decoding

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics/test: Decode from insufficient bytes

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics/test: Check unsupported versions

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics/test: Statically decode to root and pallet enums

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics/tests: Remove clones

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* blocks: Fetch block body inline

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* blocks: Rename ExtrinsicIds to ExtrinsicPartTypeIds

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics/test: Check decode as_extrinsic

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* blocks: Remove InsufficientData error

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* blocks: Return error from extrinsic_metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* extrinsics: Postpone decoding of call bytes

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* metadata_type: Rename variables

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Adjust calls path for example and tests

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Remove traces

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* book: Add extrinsics documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* book: Improve extrinsics docs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

---------

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: James Wilson <james@jsdw.me>

codegen/src/api/calls.rs

@@ -83,6 +83,11 @@ pub fn generate_calls(
             // The call structure's documentation was stripped above.
             let call_struct = quote! {
                 #struct_def
+
+                impl #crate_path::blocks::StaticExtrinsic for #struct_name {
+                    const PALLET: &'static str = #pallet_name;
+                    const CALL: &'static str = #call_name;
+                }
             };
 
             let client_fn = quote! {
@@ -106,6 +111,7 @@ pub fn generate_calls(
         .into_iter()
         .unzip();
 
+    let call_type = type_gen.resolve_type_path(call.ty.id);
     let call_ty = type_gen.resolve_type(call.ty.id);
     let docs = &call_ty.docs;
     let docs = should_gen_docs
@@ -114,6 +120,7 @@ pub fn generate_calls(
 
     Ok(quote! {
         #docs
+        pub type Call = #call_type;
         pub mod calls {
             use super::root_mod;
             use super::#types_mod_ident;