openapi_nexus/generators/python/httpx/
emit_api.rs

1//! API emission for IR operations (Python API classes).
2//!
3//! Uses sigil-stitch high-level APIs (TypeSpec, FunSpec, TypeName, FileSpec) for
4//! structured code generation with automatic import tracking. Groups operations
5//! by tag, emits one `apis/{tag}_api.py` per tag.
6
7use std::collections::{BTreeMap, HashSet};
8
9use crate::codegen::traits::file_writer::FileInfo;
10use crate::ir::types::{
11    IrOperation, IrParameter, IrPrimitive, IrRequestBody, IrResponse, IrSpec, IrTypeExpr,
12    ParameterLocation,
13};
14use heck::{ToPascalCase, ToSnakeCase};
15use sigil_stitch::code_block::CodeBlock;
16use sigil_stitch::lang::python::Python;
17use sigil_stitch::prelude::*;
18
19use super::emit_models::{api_type_name, future_annotations_header, is_object_schema};
20
21/// Generate every API file from the IR.
22pub fn generate_api_files(ir: &IrSpec, header: &str) -> Result<Vec<FileInfo>, String> {
23    let by_tag = group_by_tag(&ir.operations);
24    let mut files = Vec::with_capacity(by_tag.len());
25    for (tag, ops) in &by_tag {
26        let stem = tag.to_snake_case();
27        let filename = format!("{stem}_api.py");
28        let body = emit_api_file(tag, ops, ir, header);
29        files.push(FileInfo::api(filename, body));
30    }
31    Ok(files)
32}
33
34fn group_by_tag(operations: &[IrOperation]) -> BTreeMap<String, Vec<&IrOperation>> {
35    let mut out: BTreeMap<String, Vec<&IrOperation>> = BTreeMap::new();
36    for op in operations {
37        let tags: Vec<String> = if op.tags.is_empty() {
38            vec!["default".to_string()]
39        } else {
40            op.tags.clone()
41        };
42        for tag in tags {
43            out.entry(tag).or_default().push(op);
44        }
45    }
46    out
47}
48
49fn emit_api_file(tag: &str, ops: &[&IrOperation], ir: &IrSpec, header: &str) -> String {
50    let class_name = format!("{}Api", tag.to_pascal_case());
51    let plans: Vec<OpPlan> = ops.iter().map(|op| plan_operation(op)).collect();
52
53    let client_type = TypeName::importable("..runtime.client", "Client");
54    let error_type = TypeName::importable("..runtime.errors", "ApiError");
55
56    // __init__ method via FunSpec
57    let init_body = CodeBlock::of("self._client = client", ()).expect("static body");
58    let init = FunSpec::builder("__init__")
59        .add_param(ParameterSpec::of("self", TypeName::primitive("")))
60        .add_param(ParameterSpec::of("client", client_type))
61        .returns(TypeName::primitive("None"))
62        .body(init_body)
63        .build()
64        .expect("__init__ FunSpec builds");
65
66    let mut cls = TypeSpec::builder(&class_name, TypeKind::Class).add_method(init);
67
68    for plan in &plans {
69        cls = cls.add_method(build_api_method(plan, ir, &error_type));
70    }
71
72    let file = FileSpec::builder_with(&format!("{}_api.py", tag.to_snake_case()), Python::new())
73        .header(future_annotations_header())
74        .add_type(cls.build().expect("API TypeSpec builds"))
75        .build()
76        .expect("API FileSpec builds");
77
78    let body = file.render(120).unwrap_or_default();
79    let mut content = String::with_capacity(header.len() + body.len());
80    content.push_str(header);
81    content.push_str(&body);
82    content
83}
84
85fn build_api_method(plan: &OpPlan<'_>, ir: &IrSpec, error_type: &TypeName) -> FunSpec {
86    let mut fun = FunSpec::builder(&plan.method_name);
87
88    // self (bare, no type annotation)
89    fun = fun.add_param(ParameterSpec::of("self", TypeName::primitive("")));
90
91    // Positional params (path params)
92    for p in &plan.path_params {
93        fun = fun.add_param(ParameterSpec::of(
94            &p.var_name,
95            api_type_name(&p.param.type_expr),
96        ));
97    }
98
99    // Keyword-only separator
100    let has_keyword_params =
101        !plan.query_params.is_empty() || !plan.header_params.is_empty() || plan.body.is_some();
102    if has_keyword_params {
103        fun = fun.add_param(ParameterSpec::of("*", TypeName::primitive("")));
104    }
105
106    // Required query/header params first
107    for p in plan.query_params.iter().chain(&plan.header_params) {
108        if p.param.required {
109            fun = fun.add_param(ParameterSpec::of(
110                &p.var_name,
111                api_type_name(&p.param.type_expr),
112            ));
113        }
114    }
115
116    // Body param
117    if let Some(b) = &plan.body {
118        let ty = api_type_name(&b.type_expr);
119        if b.required {
120            fun = fun.add_param(ParameterSpec::of(&b.var_name, ty));
121        } else {
122            fun = fun.add_param(
123                ParameterSpec::builder(&b.var_name, TypeName::optional(ty))
124                    .default_value(CodeBlock::of("None", ()).expect("None"))
125                    .build()
126                    .expect("optional body param"),
127            );
128        }
129    }
130
131    // Optional query/header params last
132    for p in plan.query_params.iter().chain(&plan.header_params) {
133        if !p.param.required {
134            fun = fun.add_param(
135                ParameterSpec::builder(
136                    &p.var_name,
137                    TypeName::optional(api_type_name(&p.param.type_expr)),
138                )
139                .default_value(CodeBlock::of("None", ()).expect("None"))
140                .build()
141                .expect("optional param"),
142            );
143        }
144    }
145
146    // Return type — auto-tracked via TypeName
147    let return_type = if plan.typed_responses.is_empty() {
148        TypeName::primitive("None")
149    } else {
150        api_type_name(&plan.typed_responses[0].type_expr)
151    };
152    fun = fun.returns(return_type);
153
154    // Docstring
155    if let Some(summary) = &plan.op.summary {
156        fun = fun.doc(&format!("{summary}."));
157    }
158
159    // Method body (imperative control flow, stays as CodeBlock)
160    fun = fun.body(build_method_body(plan, ir, error_type));
161
162    fun.build().expect("API method FunSpec builds")
163}
164
165fn build_method_body(plan: &OpPlan<'_>, ir: &IrSpec, error_type: &TypeName) -> CodeBlock {
166    let mut cb = CodeBlock::builder();
167
168    // Path interpolation
169    if plan.path_params.is_empty() {
170        cb.add_statement(&format!("path = \"{}\"", plan.op.path), ());
171    } else {
172        let mut path_template = plan.op.path.clone();
173        for p in &plan.path_params {
174            let placeholder = format!("{{{}}}", p.param.name);
175            let replacement = format!("{{{}}}", p.var_name);
176            path_template = path_template.replace(&placeholder, &replacement);
177        }
178        cb.add_statement("path = %V", VerbatimStrArg(path_template));
179    }
180
181    // Query params
182    let has_query = !plan.query_params.is_empty();
183    if has_query {
184        cb.add_statement("params: dict[str, str] = {}", ());
185        for p in &plan.query_params {
186            let stringify = render_stringify(&p.var_name, &p.param.type_expr);
187            if p.param.required {
188                cb.add_statement(&format!("params[\"{}\"] = {stringify}", p.param.name), ());
189            } else {
190                cb.add_statement(&format!("if {} is not None:%>", p.var_name), ());
191                cb.add_statement(&format!("params[\"{}\"] = {stringify}%<", p.param.name), ());
192            }
193        }
194    }
195
196    // Header params
197    let has_headers = !plan.header_params.is_empty();
198    if has_headers {
199        cb.add_statement("headers: dict[str, str] = {}", ());
200        for p in &plan.header_params {
201            let stringify = render_stringify(&p.var_name, &p.param.type_expr);
202            if p.param.required {
203                cb.add_statement(&format!("headers[\"{}\"] = {stringify}", p.param.name), ());
204            } else {
205                cb.add_statement(&format!("if {} is not None:%>", p.var_name), ());
206                cb.add_statement(
207                    &format!("headers[\"{}\"] = {stringify}%<", p.param.name),
208                    (),
209                );
210            }
211        }
212    }
213
214    // Body serialization
215    let body_expr = if let Some(b) = &plan.body {
216        if is_object_type(&b.type_expr, ir) {
217            if b.required {
218                format!("{}.to_dict()", b.var_name)
219            } else {
220                format!(
221                    "{}.to_dict() if {} is not None else None",
222                    b.var_name, b.var_name
223                )
224            }
225        } else if is_array_of_objects(&b.type_expr, ir) {
226            if b.required {
227                format!("[item.to_dict() for item in {}]", b.var_name)
228            } else {
229                format!(
230                    "[item.to_dict() for item in {}] if {} is not None else None",
231                    b.var_name, b.var_name
232                )
233            }
234        } else {
235            b.var_name.clone()
236        }
237    } else {
238        String::new()
239    };
240
241    // Request call
242    let mut request_args = vec![
243        format!("\"{}\"", plan.op.method.to_uppercase()),
244        "path".to_string(),
245    ];
246    if has_query {
247        request_args.push("params=params".to_string());
248    }
249    if plan.body.is_some() {
250        request_args.push(format!("json={body_expr}"));
251    }
252    if has_headers {
253        request_args.push("headers=headers".to_string());
254    }
255
256    cb.add_statement(
257        &format!(
258            "response = self._client.request({})",
259            request_args.join(", "),
260        ),
261        (),
262    );
263
264    // Error handling
265    cb.add_statement("if response.status_code >= 400:%>", ());
266    cb.add_statement(
267        "raise %T(response.status_code, response.reason_phrase, response.content)%<",
268        (error_type.clone(),),
269    );
270
271    // Response parsing
272    if !plan.typed_responses.is_empty() {
273        let tr = &plan.typed_responses[0];
274        let parse_expr = render_response_parse(&tr.type_expr, ir);
275        cb.add_statement(&format!("return {parse_expr}"), ());
276    } else {
277        cb.add_statement("return None", ());
278    }
279
280    cb.build().expect("API method body builds")
281}
282
283fn render_stringify(var: &str, type_expr: &IrTypeExpr) -> String {
284    match type_expr {
285        IrTypeExpr::Primitive(
286            IrPrimitive::String
287            | IrPrimitive::Date
288            | IrPrimitive::DateTime
289            | IrPrimitive::Uuid
290            | IrPrimitive::StringWithFormat(_),
291        )
292        | IrTypeExpr::StringLiteral(_)
293        | IrTypeExpr::StringEnum(_)
294        | IrTypeExpr::Named(_) => format!("str({var})"),
295        IrTypeExpr::Primitive(IrPrimitive::Boolean) => format!("str({var}).lower()"),
296        IrTypeExpr::Primitive(
297            IrPrimitive::Integer
298            | IrPrimitive::IntegerWithFormat(_)
299            | IrPrimitive::Number
300            | IrPrimitive::NumberWithFormat(_),
301        ) => format!("str({var})"),
302        IrTypeExpr::Nullable(inner) => render_stringify(var, inner),
303        IrTypeExpr::Array(_) => format!("\",\".join(str(v) for v in {var})"),
304        _ => format!("str({var})"),
305    }
306}
307
308fn render_response_parse(type_expr: &IrTypeExpr, ir: &IrSpec) -> String {
309    match type_expr {
310        IrTypeExpr::Named(name) => {
311            let py_name = name.to_pascal_case();
312            if is_object_schema(name, ir) {
313                format!("{py_name}.from_dict(response.json())")
314            } else {
315                "response.json()  # type: ignore[return-value]".to_string()
316            }
317        }
318        IrTypeExpr::Array(inner) => {
319            if let IrTypeExpr::Named(name) = inner.as_ref()
320                && is_object_schema(name, ir)
321            {
322                let py_name = name.to_pascal_case();
323                return format!("[{py_name}.from_dict(item) for item in response.json()]");
324            }
325            "response.json()  # type: ignore[return-value]".to_string()
326        }
327        IrTypeExpr::Primitive(IrPrimitive::String | IrPrimitive::StringWithFormat(_)) => {
328            "response.text".to_string()
329        }
330        _ => "response.json()  # type: ignore[return-value]".to_string(),
331    }
332}
333
334fn is_object_type(type_expr: &IrTypeExpr, ir: &IrSpec) -> bool {
335    if let IrTypeExpr::Named(name) = type_expr {
336        return is_object_schema(name, ir);
337    }
338    false
339}
340
341fn is_array_of_objects(type_expr: &IrTypeExpr, ir: &IrSpec) -> bool {
342    if let IrTypeExpr::Array(inner) = type_expr
343        && let IrTypeExpr::Named(name) = inner.as_ref()
344    {
345        return is_object_schema(name, ir);
346    }
347    false
348}
349
350// ---------------------------------------------------------------------------
351// Planning
352// ---------------------------------------------------------------------------
353
354struct OpPlan<'a> {
355    op: &'a IrOperation,
356    method_name: String,
357    path_params: Vec<ParamBinding<'a>>,
358    query_params: Vec<ParamBinding<'a>>,
359    header_params: Vec<ParamBinding<'a>>,
360    body: Option<BodyBinding>,
361    typed_responses: Vec<TypedResponse>,
362}
363
364struct ParamBinding<'a> {
365    param: &'a IrParameter,
366    var_name: String,
367}
368
369struct BodyBinding {
370    var_name: String,
371    type_expr: IrTypeExpr,
372    required: bool,
373}
374
375struct TypedResponse {
376    type_expr: IrTypeExpr,
377}
378
379fn plan_operation<'a>(op: &'a IrOperation) -> OpPlan<'a> {
380    let op_id = sanitize_operation_id(&op.operation_id, &op.method, &op.path);
381    let method_name = op_id.to_snake_case();
382
383    let mut used_names: HashSet<String> = HashSet::new();
384    used_names.insert("self".to_string());
385
386    let mut path_params = Vec::new();
387    let mut query_params = Vec::new();
388    let mut header_params = Vec::new();
389
390    for p in &op.parameters {
391        let var_name = unique_name(&python_param_name(&p.name), &mut used_names);
392        let binding = ParamBinding { param: p, var_name };
393        match p.location {
394            ParameterLocation::Path => path_params.push(binding),
395            ParameterLocation::Query => query_params.push(binding),
396            ParameterLocation::Header => header_params.push(binding),
397            ParameterLocation::Cookie => header_params.push(binding),
398        }
399    }
400
401    let body = op
402        .request_body
403        .as_ref()
404        .and_then(|b| plan_body(b, &mut used_names));
405
406    let typed_responses = op.responses.iter().filter_map(plan_response).collect();
407
408    OpPlan {
409        op,
410        method_name,
411        path_params,
412        query_params,
413        header_params,
414        body,
415        typed_responses,
416    }
417}
418
419fn plan_body(b: &IrRequestBody, used_names: &mut HashSet<String>) -> Option<BodyBinding> {
420    let t = pick_body_type(b)?;
421    let var_name = unique_name("body", used_names);
422    Some(BodyBinding {
423        var_name,
424        type_expr: t,
425        required: b.required,
426    })
427}
428
429fn plan_response(r: &IrResponse) -> Option<TypedResponse> {
430    let t = pick_response_type(r)?;
431    Some(TypedResponse { type_expr: t })
432}
433
434fn pick_body_type(body: &IrRequestBody) -> Option<IrTypeExpr> {
435    body.content
436        .get("application/json")
437        .cloned()
438        .or_else(|| body.content.values().next().cloned())
439}
440
441fn pick_response_type(r: &IrResponse) -> Option<IrTypeExpr> {
442    r.content
443        .get("application/json")
444        .cloned()
445        .or_else(|| r.content.values().next().cloned())
446}
447
448fn python_param_name(name: &str) -> String {
449    let snake = name.to_snake_case();
450    if snake.is_empty() {
451        return "param".to_string();
452    }
453    match snake.as_str() {
454        "and" | "as" | "assert" | "async" | "await" | "break" | "class" | "continue" | "def"
455        | "del" | "elif" | "else" | "except" | "finally" | "for" | "from" | "global" | "if"
456        | "import" | "in" | "is" | "lambda" | "nonlocal" | "not" | "or" | "pass" | "raise"
457        | "return" | "try" | "while" | "with" | "yield" | "type" | "self" => {
458            format!("{snake}_")
459        }
460        _ => snake,
461    }
462}
463
464fn unique_name(desired: &str, used: &mut HashSet<String>) -> String {
465    if used.insert(desired.to_string()) {
466        return desired.to_string();
467    }
468    for i in 2..=u32::MAX {
469        let candidate = format!("{desired}{i}");
470        if used.insert(candidate.clone()) {
471            return candidate;
472        }
473    }
474    unreachable!("name collision space exhausted")
475}
476
477fn sanitize_operation_id(op_id: &str, method: &str, path: &str) -> String {
478    if !op_id.is_empty() {
479        return op_id.to_string();
480    }
481    let path_part: String = path
482        .chars()
483        .map(|c| if c.is_alphanumeric() { c } else { '_' })
484        .collect();
485    format!("{method}_{path_part}")
486}
openapi_nexus/generators/python/httpx/emit_api.rs

openapi_nexus/generators/python/httpx/
emit_api.rs
