From c6d7e532c4e010f55ab8c6b7cfd8b36d44779725 Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Sun, 12 Apr 2026 04:22:01 +0800
Subject: feat: implement link extraction and interactive navigation via
 numbered tags in the browser

---
 src/core/browser.cc | 104 +++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 94 insertions(+), 10 deletions(-)

(limited to 'src/core')

diff --git a/src/core/browser.cc b/src/core/browser.cc
index 4225986..8bd921c 100644
--- a/src/core/browser.cc
+++ b/src/core/browser.cc
@@ -23,17 +23,24 @@
 #include "ricochet/render/renderer.hh"
 #include "ricochet/tui/terminal.hh"
 #include <cstddef>
+#include <exception>
 #include <iostream>
 
 namespace ricochet::core {
 
+struct PageData
+{
+  std::vector<std::string> lines;
+  std::vector<std::string> links;
+};
+
 namespace {
-std::vector<std::string> load_page( std::string_view url )
+PageData load_page( std::string_view url )
 {
   const net::HttpClient client;
   auto response_result = client.fetch( url );
   if ( !response_result.has_value() ) {
-    return { "[!] Failed to load: " + std::string( url ) };
+    return { .lines = { "[!] Failed to load: " + std::string( url ) }, .links = {} };
   }
 
   const parser::HtmlLexer lexer;
@@ -41,20 +48,20 @@ std::vector<std::string> load_page( std::string_view url )
   const render::Renderer renderer;
 
   const auto dom_root = builder.build( lexer.tokenize( response_result.value().body ) );
-  const std::string text = renderer.render( dom_root );
+  const render::RenderResult result = renderer.render( dom_root );
 
   std::vector<std::string> lines;
   std::size_t start = 0;
-  while ( start < text.length() ) {
-    const std::size_t end = text.find( '\n', start );
+  while ( start < result.text.length() ) {
+    const std::size_t end = result.text.find( '\n', start );
     if ( end == std::string::npos ) {
-      lines.push_back( text.substr( start ) );
+      lines.push_back( result.text.substr( start ) );
       break;
     }
-    lines.push_back( text.substr( start, end - start ) );
+    lines.push_back( result.text.substr( start, end - start ) );
     start = end + 1;
   }
-  return lines;
+  return { .lines = lines, .links = result.links };
 }
 
 void draw_view( const tui::Terminal& terminal,
@@ -73,7 +80,7 @@ void draw_view( const tui::Terminal& terminal,
       std::cout << "~\r\n";
     }
   }
-  std::cout << "\033[7m URL: " << url << " | [j/k] Scroll [/] Jump [q] Quit \033[0m";
+  std::cout << "\033[7m URL: " << url << " | [j/k] Scroll [/] Jump [f] Follow [q] Quit \033[0m";
   std::cout.flush();
 }
 
@@ -115,6 +122,79 @@ std::string get_url_input( const tui::Terminal& terminal )
   return input;
 }
 
+std::string get_link_input( const tui::Terminal& terminal )
+{
+  auto [width, height] = terminal.get_size();
+  terminal.move_cursor( height, 1 );
+  std::cout << "\x1b[2K\033[7m Follow Link [#]: \033[0m ";
+  std::cout.flush();
+
+  std::string num_input;
+  terminal.show_cursor( true );
+  while ( true ) {
+    const char ch = terminal.read_key();
+    if ( ch == '\r' || ch == '\n' ) {
+      break;
+    }
+    if ( ch == 27 ) {
+      num_input.clear();
+      break;
+    }
+    if ( ch == 127 || ch == 8 ) {
+      if ( !num_input.empty() ) {
+        num_input.pop_back();
+        std::cout << "\b \b";
+        std::cout.flush();
+      }
+    } else if ( std::isdigit( static_cast<unsigned char>( ch ) ) ) {
+      num_input += ch;
+      std::cout << ch;
+      std::cout.flush();
+    }
+  }
+  terminal.show_cursor( false );
+  return num_input;
+}
+
+void handle_follow_link( const tui::Terminal& terminal,
+                         const std::vector<std::string>& links,
+                         std::string& current_url,
+                         bool& navigate )
+{
+  const std::string num_input = get_link_input( terminal );
+  if ( !num_input.empty() ) {
+    try {
+      const std::size_t index = std::stoul( num_input );
+      if ( index > 0 && index <= links.size() ) {
+        std::string target = links[index - 1];
+
+        if ( target.starts_with( "/" ) ) {
+          if ( target.starts_with( "//" ) ) {
+            target = "https:" + target; // "//example.com"
+          } else {
+            const std::size_t slash_pos = current_url.find( '/', 8 ); // 跳过 https://
+            const std::string domain
+              = ( slash_pos == std::string::npos ) ? current_url : current_url.substr( 0, slash_pos );
+            target = domain + target; // "/about" -> "https://gnu.org/about"
+          }
+        } else if ( !target.starts_with( "http" ) ) {
+          const std::size_t last_slash = current_url.rfind( '/' );
+          if ( last_slash > 7 ) {
+            target = current_url.substr( 0, last_slash + 1 ) + target;
+          } else {
+            target = current_url + "/" + target;
+          }
+        }
+
+        current_url = target;
+        navigate = true;
+      }
+    } catch ( const std::exception& e ) {
+      (void)e; // NOLINT
+    }
+  }
+}
+
 } // namespace
 
 int Browser::run( std::string_view initial_url )
@@ -126,7 +206,9 @@ int Browser::run( std::string_view initial_url )
   terminal.clear_screen();
 
   while ( !current_url.empty() ) {
-    auto lines = load_page( current_url );
+    auto page_data = load_page( current_url );
+    const auto& lines = page_data.lines;
+    const auto& links = page_data.links;
     std::size_t scroll_y = 0;
     bool navigate = false;
 
@@ -151,6 +233,8 @@ int Browser::run( std::string_view initial_url )
           current_url = std::move( next_url );
           navigate = true;
         }
+      } else if ( c == 'f' ) {
+        handle_follow_link( terminal, links, current_url, navigate );
       }
     }
   }
-- 
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