add method generation

4 files changed, 555 insertions, 5 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 47254d3..ea64452 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -242,6 +242,7 @@ name = "generator"
 version = "0.1.0"
 dependencies = [
  "eyre",
+ "heck",
  "serde",
  "serde_json",
  "url",
@@ -279,6 +280,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
 
 [[package]]
+name = "heck"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
+
+[[package]]
 name = "http"
 version = "0.2.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/generator/Cargo.toml b/generator/Cargo.toml
index 91f832e..21821e0 100644
--- a/generator/Cargo.toml
+++ b/generator/Cargo.toml
@@ -7,6 +7,7 @@ edition = "2021"
 
 [dependencies]
 eyre = "0.6.11"
+heck = "0.4.1"
 serde = { version = "1.0.195", features = ["derive"] }
 serde_json = "1.0.111"
 url = { version = "2.5.0", features = ["serde"] }
diff --git a/generator/src/main.rs b/generator/src/main.rs
index 3d5900c..79fd479 100644
--- a/generator/src/main.rs
+++ b/generator/src/main.rs
@@ -2,16 +2,556 @@ use std::ffi::OsString;
 
 mod openapi;
 
+use eyre::Context;
+use heck::{ToPascalCase, ToSnakeCase};
+use openapi::{
+    MaybeRef, OpenApiV2, Operation, Parameter, ParameterIn, ParameterType, Primitive, Response,
+    Schema, SchemaType,
+};
+use std::fmt::Write;
+
 fn main() -> eyre::Result<()> {
     let spec = get_spec()?;
-    dbg!(spec);
+    let mut s = String::new();
+    s.push_str("impl Forgejo {\n");
+    for (path, item) in &spec.paths {
+        s.push_str(&create_methods_for_path(&spec, path, item).wrap_err_with(|| path.clone())?);
+    }
+    s.push('}');
+    save_generated(&mut s)?;
     Ok(())
 }
 
-fn get_spec() -> eyre::Result<openapi::OpenApiV2> {
+fn get_spec() -> eyre::Result<OpenApiV2> {
     let path = std::env::var_os("FORGEJO_API_SPEC_PATH")
-        .unwrap_or_else(|| OsString::from("./api_spec.json"));
+        .unwrap_or_else(|| OsString::from("./swagger.v1.json"));
     let file = std::fs::read(path)?;
-    let spec = serde_json::from_slice::<openapi::OpenApiV2>(&file)?;
+    let spec = serde_json::from_slice::<OpenApiV2>(&file)?;
     Ok(spec)
 }
+
+fn save_generated(contents: &str) -> eyre::Result<()> {
+    let path = std::env::var_os("FORGEJO_API_GENERATED_PATH")
+        .unwrap_or_else(|| OsString::from("./src/generated.rs"));
+    std::fs::write(path, contents)?;
+    Ok(())
+}
+
+fn create_methods_for_path(
+    spec: &OpenApiV2,
+    path: &str,
+    item: &openapi::PathItem,
+) -> eyre::Result<String> {
+    let mut s = String::new();
+    if let Some(op) = &item.get {
+        s.push_str(&create_get_method(spec, path, op).wrap_err("GET")?);
+    }
+    if let Some(op) = &item.put {
+        s.push_str(&create_put_method(spec, path, op).wrap_err("PUT")?);
+    }
+    if let Some(op) = &item.post {
+        s.push_str(&create_post_method(spec, path, op).wrap_err("POST")?);
+    }
+    if let Some(op) = &item.delete {
+        s.push_str(&create_delete_method(spec, path, op).wrap_err("DELETE")?);
+    }
+    if let Some(op) = &item.options {
+        s.push_str(&create_options_method(spec, path, op).wrap_err("OPTIONS")?);
+    }
+    if let Some(op) = &item.head {
+        s.push_str(&create_head_method(spec, path, op).wrap_err("HEAD")?);
+    }
+    if let Some(op) = &item.patch {
+        s.push_str(&create_patch_method(spec, path, op).wrap_err("PATCH")?);
+    }
+    Ok(s)
+}
+
+fn fn_signature_from_op(spec: &OpenApiV2, op: &Operation) -> eyre::Result<String> {
+    let name = op
+        .operation_id
+        .as_deref()
+        .ok_or_else(|| eyre::eyre!("operation did not have id"))?
+        .to_snake_case()
+        .replace("o_auth2", "oauth2");
+    let args = fn_args_from_op(spec, op)?;
+    let ty = fn_return_from_op(spec, op)?;
+    Ok(format!("fn {name}({args}) -> Result<{ty}, ForgejoError>"))
+}
+
+fn fn_args_from_op(spec: &OpenApiV2, op: &Operation) -> eyre::Result<String> {
+    let mut args = "&self".to_string();
+    let mut has_query = false;
+    let mut has_headers = false;
+    let mut has_form = false;
+    if let Some(params) = &op.parameters {
+        for param in params {
+            let param = match &param {
+                MaybeRef::Value { value } => value,
+                MaybeRef::Ref { _ref } => eyre::bail!("todo: add deref parameters"),
+            };
+            match param._in {
+                ParameterIn::Path => {
+                    let type_name = path_param_type(&param)?;
+                    args.push_str(", ");
+                    args.push_str(&sanitize_ident(param.name.to_snake_case()));
+                    args.push_str(": ");
+                    args.push_str(type_name);
+                }
+                ParameterIn::Query => has_query = true,
+                ParameterIn::Header => has_headers = true,
+                ParameterIn::Body => {
+                    let schema_ref = param.schema.as_ref().unwrap();
+                    let ty = schema_ref_type_name(spec, &schema_ref)?;
+                    args.push_str(", ");
+                    args.push_str(&sanitize_ident(param.name.to_snake_case()));
+                    args.push_str(": ");
+                    args.push_str(&ty);
+                }
+                ParameterIn::FormData => {
+                    args.push_str(", ");
+                    args.push_str(&sanitize_ident(param.name.to_snake_case()));
+                    args.push_str(": Vec<u8>");
+                }
+            }
+        }
+    }
+    if has_query {
+        let query_ty = query_struct_name(op)?;
+        args.push_str(", query: ");
+        args.push_str(&query_ty);
+    }
+    Ok(args)
+}
+
+fn query_struct_name(op: &Operation) -> eyre::Result<String> {
+    let mut ty = op
+        .operation_id
+        .as_deref()
+        .ok_or_else(|| eyre::eyre!("operation did not have id"))?
+        .to_pascal_case()
+        .replace("o_auth2", "oauth2");
+    ty.push_str("Query");
+    Ok(ty)
+}
+
+fn fn_return_from_op(spec: &OpenApiV2, op: &Operation) -> eyre::Result<String> {
+    let mut names = op
+        .responses
+        .http_codes
+        .iter()
+        .filter(|(k, _)| k.starts_with("2"))
+        .map(|(_, v)| response_ref_type_name(spec, v))
+        .collect::<Result<Vec<_>, _>>()?;
+
+    names.sort();
+    names.dedup();
+    let name = match names.len() {
+        0 => eyre::bail!("no type name found"),
+        1 => {
+            let name = names.pop().unwrap();
+            if name == "empty" {
+                "()".into()
+            } else {
+                name
+            }
+        }
+        2 if names[0] == "empty" || names[1] == "empty" => {
+            let name = if names[0] == "empty" {
+                names.remove(1)
+            } else {
+                names.remove(0)
+            };
+            format!("Option<{name}>")
+        }
+        _ => eyre::bail!("too many possible return types"),
+    };
+
+    Ok(name)
+}
+
+fn response_ref_type_name(spec: &OpenApiV2, schema: &MaybeRef<Response>) -> eyre::Result<String> {
+    let (name, response) = deref_response(spec, schema)?;
+    if let Some(schema) = &response.schema {
+        schema_ref_type_name(spec, schema)
+    } else if let Some(name) = name {
+        Ok(name.into())
+    } else {
+        Ok("()".into())
+    }
+}
+
+fn schema_ref_type_name(spec: &OpenApiV2, schema: &MaybeRef<Schema>) -> eyre::Result<String> {
+    let (name, schema) = deref_definition(spec, &schema)?;
+    schema_type_name(spec, name, schema)
+}
+
+fn schema_type_name(
+    spec: &OpenApiV2,
+    definition_name: Option<&str>,
+    schema: &Schema,
+) -> eyre::Result<String> {
+    if let Some(ty) = &schema._type {
+        match ty {
+            SchemaType::One(prim) => {
+                let name = match prim {
+                    Primitive::String => match schema.format.as_deref() {
+                        Some("date") => "time::Date",
+                        Some("date-time") => "time::OffsetDateTime",
+                        _ => "String",
+                    }
+                    .to_string(),
+                    Primitive::Number => match schema.format.as_deref() {
+                        Some("float") => "f32",
+                        Some("double") => "f64",
+                        _ => "f64",
+                    }
+                    .to_string(),
+                    Primitive::Integer => match schema.format.as_deref() {
+                        Some("int32") => "u32",
+                        Some("int64") => "u64",
+                        _ => "u32",
+                    }
+                    .to_string(),
+                    Primitive::Boolean => "bool".to_string(),
+                    Primitive::Array => {
+                        let item_name = match &schema.items {
+                            Some(item_schema) => schema_ref_type_name(spec, item_schema)?,
+                            None => "serde_json::Value".into(),
+                        };
+                        format!("Vec<{item_name}>")
+                    }
+                    Primitive::Null => "()".to_string(),
+                    Primitive::Object => {
+                        match (&schema.title, definition_name) {
+                            // Some of the titles are actually descriptions; not sure why
+                            // Checking for a space filters that out
+                            (Some(title), _) if !title.contains(' ') => title.to_string(),
+                            (_, Some(definition_name)) => definition_name.to_string(),
+                            (_, None) => "serde_json::Map".to_string(),
+                        }
+                    }
+                };
+                Ok(name.to_owned())
+            }
+            SchemaType::List(list) => todo!(),
+        }
+    } else {
+        Ok("()".into())
+    }
+}
+
+fn path_param_type(param: &Parameter) -> eyre::Result<&'static str> {
+    let _type = param
+        ._type
+        .as_ref()
+        .ok_or_else(|| eyre::eyre!("no type provided for path param"))?;
+    let type_name = match _type {
+        ParameterType::String => match param.format.as_deref() {
+            Some("date") => "time::Date",
+            Some("date-time") => "time::OffsetDateTime",
+            _ => "&str",
+        },
+        ParameterType::Number => match param.format.as_deref() {
+            Some("float") => "f32",
+            Some("double") => "f64",
+            _ => "f64",
+        },
+        ParameterType::Integer => match param.format.as_deref() {
+            Some("int32") => "u32",
+            Some("int64") => "u64",
+            _ => "u32",
+        },
+        ParameterType::Boolean => "bool",
+        ParameterType::Array => eyre::bail!("todo: support returning arrays"),
+        ParameterType::File => "Vec<u8>",
+    };
+    Ok(type_name)
+}
+
+fn method_docs(op: &Operation) -> eyre::Result<String> {
+    let mut out = String::new();
+    let mut prev = false;
+    if let Some(summary) = &op.summary {
+        write!(&mut out, "/// {summary}\n")?;
+        prev = true;
+    }
+    if let Some(params) = &op.parameters {
+        if prev {
+            out.push_str("///\n");
+        }
+        for param in params {
+            let param = match &param {
+                MaybeRef::Value { value } => value,
+                MaybeRef::Ref { _ref } => eyre::bail!("pipis"),
+            };
+            match param._in {
+                ParameterIn::Path | ParameterIn::Body | ParameterIn::FormData => {
+                    write!(&mut out, "/// - `{}`", param.name)?;
+                    if let Some(description) = &param.description {
+                        write!(&mut out, ": {}", description)?;
+                    }
+                    writeln!(&mut out)?;
+                }
+                _ => (),
+            }
+        }
+    }
+    Ok(out)
+}
+
+fn deref_response<'a>(
+    spec: &'a OpenApiV2,
+    r: &'a MaybeRef<Response>,
+) -> eyre::Result<(Option<&'a str>, &'a Response)> {
+    let r = match r {
+        MaybeRef::Value { value } => return Ok((None, value)),
+        MaybeRef::Ref { _ref } => _ref,
+    };
+    let name = r
+        .strip_prefix("#/responses/")
+        .ok_or_else(|| eyre::eyre!("invalid response reference"))?;
+    let global_responses = spec
+        .responses
+        .as_ref()
+        .ok_or_else(|| eyre::eyre!("no global responses"))?;
+    let response = global_responses
+        .get(name)
+        .ok_or_else(|| eyre::eyre!("referenced response does not exist"))?;
+    Ok((Some(name), response))
+}
+
+fn deref_definition<'a>(
+    spec: &'a OpenApiV2,
+    r: &'a MaybeRef<Schema>,
+) -> eyre::Result<(Option<&'a str>, &'a Schema)> {
+    let r = match r {
+        MaybeRef::Value { value } => return Ok((None, value)),
+        MaybeRef::Ref { _ref } => _ref,
+    };
+    let name = r
+        .strip_prefix("#/definitions/")
+        .ok_or_else(|| eyre::eyre!("invalid definition reference"))?;
+    let global_definitions = spec
+        .definitions
+        .as_ref()
+        .ok_or_else(|| eyre::eyre!("no global definitions"))?;
+    let definition = global_definitions
+        .get(name)
+        .ok_or_else(|| eyre::eyre!("referenced definition does not exist"))?;
+    Ok((Some(name), definition))
+}
+
+fn create_method_body(
+    spec: &OpenApiV2,
+    method: &str,
+    path: &str,
+    op: &Operation,
+) -> eyre::Result<String> {
+    let request = create_method_request(spec, method, path, op)?;
+    let response = create_method_response(spec, method, path, op)?;
+    Ok(format!("{request}\n    {response}"))
+}
+
+fn create_method_request(
+    spec: &OpenApiV2,
+    method: &str,
+    path: &str,
+    op: &Operation,
+) -> eyre::Result<String> {
+    let mut has_query = false;
+    let mut has_headers = false;
+    let mut body_method = String::new();
+    if let Some(params) = &op.parameters {
+        for param in params {
+            let param = match &param {
+                MaybeRef::Value { value } => value,
+                MaybeRef::Ref { _ref } => eyre::bail!("todo: add deref parameters"),
+            };
+            match param._in {
+                ParameterIn::Path => (/* do nothing */),
+                ParameterIn::Query => has_query = true,
+                ParameterIn::Header => has_headers = true,
+                ParameterIn::Body => {
+                    if !body_method.is_empty() {
+                        eyre::bail!("cannot have more than one body parameter");
+                    }
+                    if param_is_string(spec, param)? {
+                        body_method = format!(".body({})", param.name);
+                    } else {
+                        body_method = format!(".json({})?", param.name);
+                    }
+                }
+                ParameterIn::FormData => {
+                    if !body_method.is_empty() {
+                        eyre::bail!("cannot have more than one body parameter");
+                    }
+                    body_method = format!(".multipart(reqwest::multipart::Form::new().part(\"attachment\", reqwest::multipart::Part::bytes({}).file_name(\"file\").mime_str(\"*/*\").unwrap()))", param.name);
+                }
+            }
+        }
+    }
+    let mut fmt_str = path.to_string();
+    let mut fmt_args = String::new();
+    if has_query {
+        fmt_str.push_str("?{}");
+        fmt_args.push_str(", query");
+    }
+    let path_arg = if fmt_str.contains("{") {
+        format!("&format!(\"{fmt_str}\"{fmt_args})")
+    } else {
+        format!("\"{fmt_str}\"")
+    };
+
+    let out = format!("let request = self.{method}({path_arg}){body_method}.build()?;");
+    Ok(out)
+}
+
+fn create_method_response(
+    spec: &OpenApiV2,
+    method: &str,
+    path: &str,
+    op: &Operation,
+) -> eyre::Result<String> {
+    let mut has_empty = false;
+    let mut only_empty = true;
+    for (_, res) in &op.responses.http_codes {
+        let name = response_ref_type_name(spec, res)?;
+        if name == "()" || name == "empty" {
+            has_empty = true;
+        } else {
+            only_empty = false;
+        }
+    }
+    let optional = has_empty && !only_empty;
+    let mut out = String::new();
+    out.push_str("let response = self.execute(request).await?;\n");
+    out.push_str("match response.status().as_u16() {\n");
+    for (code, res) in &op.responses.http_codes {
+        let (_, res) = deref_response(spec, res)?;
+        if code.starts_with("4") {
+            continue;
+        }
+        out.push_str(code);
+        out.push_str(" => ");
+        let handler = match &res.schema {
+            Some(schema) if schema_is_string(spec, schema)? => {
+                if optional {
+                    "Ok(Some(response.text().await?))"
+                } else {
+                    "Ok(response.text().await?)"
+                }
+            }
+            Some(_) => {
+                if optional {
+                    "Ok(Some(response.json().await?))"
+                } else {
+                    "Ok(response.json().await?)"
+                }
+            }
+            None => {
+                if optional {
+                    "Ok(None)"
+                } else {
+                    "Ok(())"
+                }
+            }
+        };
+        out.push_str(handler);
+        out.push_str(",\n");
+    }
+    out.push_str("_ => Err(ForgejoError::UnexpectedStatusCode)\n");
+    out.push_str("}\n");
+
+    Ok(out)
+}
+
+fn schema_is_string(spec: &OpenApiV2, schema: &MaybeRef<Schema>) -> eyre::Result<bool> {
+    let (_, schema) = deref_definition(spec, schema)?;
+    let is_str = match schema._type {
+        Some(SchemaType::One(Primitive::String)) => true,
+        _ => false,
+    };
+    Ok(is_str)
+}
+
+fn param_is_string(spec: &OpenApiV2, param: &Parameter) -> eyre::Result<bool> {
+    match param._in {
+        ParameterIn::Body => {
+            let schema_ref = param
+                .schema
+                .as_ref()
+                .ok_or_else(|| eyre::eyre!("body param did not have schema"))?;
+            schema_is_string(spec, schema_ref)
+        }
+        _ => {
+            let is_str = match param._type {
+                Some(ParameterType::String) => true,
+                _ => false,
+            };
+            Ok(is_str)
+        }
+    }
+}
+
+fn create_get_method(spec: &OpenApiV2, path: &str, op: &Operation) -> eyre::Result<String> {
+    let doc = method_docs(op)?;
+    let sig = fn_signature_from_op(spec, op)?;
+    let body = create_method_body(spec, "get", path, op)?;
+    Ok(format!("{doc}{sig} {{\n    {body}\n}}\n\n"))
+}
+
+fn create_put_method(spec: &OpenApiV2, path: &str, op: &Operation) -> eyre::Result<String> {
+    let doc = method_docs(op)?;
+    let sig = fn_signature_from_op(spec, op)?;
+    let body = create_method_body(spec, "put", path, op)?;
+    Ok(format!("{doc}{sig} {{\n    {body}\n}}\n\n"))
+}
+
+fn create_post_method(spec: &OpenApiV2, path: &str, op: &Operation) -> eyre::Result<String> {
+    let doc = method_docs(op)?;
+    let sig = fn_signature_from_op(spec, op)?;
+    let body = create_method_body(spec, "post", path, op)?;
+    Ok(format!("{doc}{sig} {{\n    {body}\n}}\n\n"))
+}
+
+fn create_delete_method(spec: &OpenApiV2, path: &str, op: &Operation) -> eyre::Result<String> {
+    let doc = method_docs(op)?;
+    let sig = fn_signature_from_op(spec, op)?;
+    let body = create_method_body(spec, "delete", path, op)?;
+    Ok(format!("{doc}{sig} {{\n    {body}\n}}\n\n"))
+}
+
+fn create_options_method(spec: &OpenApiV2, path: &str, op: &Operation) -> eyre::Result<String> {
+    let doc = method_docs(op)?;
+    let sig = fn_signature_from_op(spec, op)?;
+    let body = create_method_body(spec, "options", path, op)?;
+    Ok(format!("{doc}{sig} {{\n    {body}\n}}\n\n"))
+}
+
+fn create_head_method(spec: &OpenApiV2, path: &str, op: &Operation) -> eyre::Result<String> {
+    let doc = method_docs(op)?;
+    let sig = fn_signature_from_op(spec, op)?;
+    let body = create_method_body(spec, "head", path, op)?;
+    Ok(format!("{doc}{sig} {{\n    {body}\n}}\n\n"))
+}
+
+fn create_patch_method(spec: &OpenApiV2, path: &str, op: &Operation) -> eyre::Result<String> {
+    let doc = method_docs(op)?;
+    let sig = fn_signature_from_op(spec, op)?;
+    let body = create_method_body(spec, "patch", path, op)?;
+    Ok(format!("{doc}{sig} {{\n    {body}\n}}\n\n"))
+}
+
+fn sanitize_ident(mut s: String) -> String {
+    let keywords = [
+        "as", "break", "const", "continue", "crate", "else", "enum", "extern", "false", "fn",
+        "for", "if", "impl", "in", "let", "loop", "match", "mod", "move", "mut", "pub", "ref",
+        "return", "self", "Self", "static", "struct", "super", "trait", "true", "type", "unsafe",
+        "use", "where", "while",
+    ];
+    if keywords.contains(&&*s) {
+        s.insert_str(0, "r#");
+    }
+    s
+}
diff --git a/generator/src/openapi.rs b/generator/src/openapi.rs
index 843a20d..f86ab88 100644
--- a/generator/src/openapi.rs
+++ b/generator/src/openapi.rs
@@ -185,7 +185,7 @@ pub struct Responses {
 #[serde(rename_all(deserialize = "camelCase"))]
 pub struct Response {
     pub description: String,
-    pub schema: Option<Schema>,
+    pub schema: Option<MaybeRef<Schema>>,
     pub headers: Option<BTreeMap<String, Header>>,
     pub examples: Option<BTreeMap<String, serde_json::Value>>,
 }
@@ -248,6 +248,8 @@ pub struct Schema {
     pub _enum: Option<Vec<serde_json::Value>>,
     #[serde(rename = "type")]
     pub _type: Option<SchemaType>,
+    pub properties: Option<BTreeMap<String, MaybeRef<Schema>>>,
+    pub items: Option<Box<MaybeRef<Schema>>>,
 
     pub discriminator: Option<String>,
     pub read_only: Option<bool>,