1 files changed, 196 insertions, 0 deletions
diff --git a/cli/util/import_map.rs b/cli/util/import_map.rs
new file mode 100644
index 000000000..e8fea1e03
--- /dev/null
+++ b/cli/util/import_map.rs
@@ -0,0 +1,196 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+use deno_ast::ParsedSource;
+use deno_core::error::AnyError;
+use deno_core::ModuleSpecifier;
+use deno_graph::DefaultModuleAnalyzer;
+use deno_graph::MediaType;
+use deno_graph::TypeScriptReference;
+use import_map::ImportMap;
+
+pub struct ImportMapUnfurler {
+  import_map: ImportMap,
+}
+
+impl ImportMapUnfurler {
+  pub fn new(import_map: ImportMap) -> Self {
+    Self { import_map }
+  }
+
+  pub fn unfurl(
+    &self,
+    url: &ModuleSpecifier,
+    data: Vec<u8>,
+  ) -> Result<Vec<u8>, AnyError> {
+    let media_type = MediaType::from_specifier(url);
+
+    match media_type {
+      MediaType::JavaScript
+      | MediaType::Jsx
+      | MediaType::Mjs
+      | MediaType::Cjs
+      | MediaType::TypeScript
+      | MediaType::Mts
+      | MediaType::Cts
+      | MediaType::Dts
+      | MediaType::Dmts
+      | MediaType::Dcts
+      | MediaType::Tsx => {
+        // continue
+      }
+      MediaType::SourceMap
+      | MediaType::Unknown
+      | MediaType::Json
+      | MediaType::Wasm
+      | MediaType::TsBuildInfo => {
+        // not unfurlable data
+        return Ok(data);
+      }
+    }
+
+    let text = String::from_utf8(data)?;
+    let parsed_source = deno_ast::parse_module(deno_ast::ParseParams {
+      specifier: url.to_string(),
+      text_info: deno_ast::SourceTextInfo::from_string(text),
+      media_type,
+      capture_tokens: false,
+      maybe_syntax: None,
+      scope_analysis: false,
+    })?;
+    let mut text_changes = Vec::new();
+    let module_info = DefaultModuleAnalyzer::module_info(&parsed_source);
+    let mut analyze_specifier =
+      |specifier: &str, range: &deno_graph::PositionRange| {
+        let resolved = self.import_map.resolve(specifier, url);
+        if let Ok(resolved) = resolved {
+          let new_text = if resolved.scheme() == "file" {
+            format!("./{}", url.make_relative(&resolved).unwrap())
+          } else {
+            resolved.to_string()
+          };
+          text_changes.push(deno_ast::TextChange {
+            range: to_range(&parsed_source, range),
+            new_text,
+          });
+        }
+      };
+    for dep in &module_info.dependencies {
+      analyze_specifier(&dep.specifier, &dep.specifier_range);
+    }
+    for ts_ref in &module_info.ts_references {
+      let specifier_with_range = match ts_ref {
+        TypeScriptReference::Path(range) => range,
+        TypeScriptReference::Types(range) => range,
+      };
+      analyze_specifier(
+        &specifier_with_range.text,
+        &specifier_with_range.range,
+      );
+    }
+    for specifier_with_range in &module_info.jsdoc_imports {
+      analyze_specifier(
+        &specifier_with_range.text,
+        &specifier_with_range.range,
+      );
+    }
+    if let Some(specifier_with_range) = &module_info.jsx_import_source {
+      analyze_specifier(
+        &specifier_with_range.text,
+        &specifier_with_range.range,
+      );
+    }
+    Ok(
+      deno_ast::apply_text_changes(
+        parsed_source.text_info().text_str(),
+        text_changes,
+      )
+      .into_bytes(),
+    )
+  }
+
+  #[cfg(test)]
+  fn unfurl_to_string(
+    &self,
+    url: &ModuleSpecifier,
+    data: Vec<u8>,
+  ) -> Result<String, AnyError> {
+    let data = self.unfurl(url, data)?;
+    let content = String::from_utf8(data)?;
+    Ok(content)
+  }
+}
+
+fn to_range(
+  parsed_source: &ParsedSource,
+  range: &deno_graph::PositionRange,
+) -> std::ops::Range<usize> {
+  let mut range = range
+    .as_source_range(parsed_source.text_info())
+    .as_byte_range(parsed_source.text_info().range().start);
+  let text = &parsed_source.text_info().text_str()[range.clone()];
+  if text.starts_with('"') || text.starts_with('\'') {
+    range.start += 1;
+  }
+  if text.ends_with('"') || text.ends_with('\'') {
+    range.end -= 1;
+  }
+  range
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use deno_ast::ModuleSpecifier;
+  use deno_core::serde_json::json;
+  use import_map::ImportMapWithDiagnostics;
+  use pretty_assertions::assert_eq;
+
+  #[test]
+  fn test_unfurling() {
+    let deno_json_url =
+      ModuleSpecifier::parse("file:///dev/deno.json").unwrap();
+    let value = json!({
+      "imports": {
+        "express": "npm:express@5",
+        "lib/": "./lib/",
+        "fizz": "./fizz/mod.ts"
+      }
+    });
+    let ImportMapWithDiagnostics { import_map, .. } =
+      import_map::parse_from_value(&deno_json_url, value).unwrap();
+    let unfurler = ImportMapUnfurler::new(import_map);
+
+    // Unfurling TS file should apply changes.
+    {
+      let source_code = r#"import express from "express";"
+import foo from "lib/foo.ts";
+import bar from "lib/bar.ts";
+import fizz from "fizz";
+"#;
+      let specifier = ModuleSpecifier::parse("file:///dev/mod.ts").unwrap();
+      let unfurled_source = unfurler
+        .unfurl_to_string(&specifier, source_code.as_bytes().to_vec())
+        .unwrap();
+      let expected_source = r#"import express from "npm:express@5";"
+import foo from "./lib/foo.ts";
+import bar from "./lib/bar.ts";
+import fizz from "./fizz/mod.ts";
+"#;
+      assert_eq!(unfurled_source, expected_source);
+    }
+
+    // Unfurling file with "unknown" media type should leave it as is
+    {
+      let source_code = r#"import express from "express";"
+import foo from "lib/foo.ts";
+import bar from "lib/bar.ts";
+import fizz from "fizz";
+"#;
+      let specifier = ModuleSpecifier::parse("file:///dev/mod").unwrap();
+      let unfurled_source = unfurler
+        .unfurl_to_string(&specifier, source_code.as_bytes().to_vec())
+        .unwrap();
+      assert_eq!(unfurled_source, source_code);
+    }
+  }
+}