Add shellgen core and backends modules

app/shellgen/core/generator.py

@@ -0,0 +1,128 @@
+"""Command generation logic."""
+
+from dataclasses import dataclass
+from typing import Optional
+
+from .prompts import PromptTemplates
+
+
+@dataclass
+class GenerationResult:
+    """Result of command generation."""
+
+    command: str
+    explanation: str
+    confidence: float
+
+
+class CommandGenerator:
+    """Generate shell commands from natural language descriptions."""
+
+    def __init__(self, backend):
+        """Initialize the command generator.
+
+        Args:
+            backend: LLM backend instance for generating commands.
+        """
+        self.backend = backend
+        self.templates = PromptTemplates()
+
+    def generate(
+        self,
+        description: str,
+        shell: str = "bash",
+        context: Optional[str] = None,
+    ) -> GenerationResult:
+        """Generate a shell command from natural language.
+
+        Args:
+            description: Natural language description of what to do.
+            shell: Target shell (bash or zsh).
+            context: Optional context (current directory, files, etc.).
+
+        Returns:
+            GenerationResult with command, explanation, and confidence.
+        """
+        prompt = self.templates.generate_prompt(description, shell, context)
+
+        response = self.backend.generate(prompt)
+
+        command = self._extract_command(response)
+        explanation = self._extract_explanation(response)
+        confidence = self._estimate_confidence(response)
+
+        return GenerationResult(
+            command=command.strip(),
+            explanation=explanation.strip(),
+            confidence=confidence,
+        )
+
+    def _extract_command(self, response: str) -> str:
+        """Extract the shell command from LLM response."""
+        lines = response.strip().split("\n")
+        command = ""
+
+        for line in lines:
+            line = line.strip()
+            if line.startswith("```"):
+                continue
+            if line.startswith("Command:") or line.startswith("```"):
+                if "```" in line:
+                    parts = line.split("```")
+                    for part in parts:
+                        if part.strip() and not part.strip().startswith("Command"):
+                            command = part.strip()
+                            break
+                else:
+                    command = line.replace("Command:", "").strip()
+            elif line and not line.startswith("#") and not line.startswith("//"):
+                if command:
+                    command += " " + line
+                else:
+                    command = line
+
+        if not command:
+            for line in lines:
+                if line.startswith("$") or line.startswith("!"):
+                    command = line[1:].strip()
+                    break
+
+        return command if command else response.strip()
+
+    def _extract_explanation(self, response: str) -> str:
+        """Extract the explanation from LLM response."""
+        lines = response.strip().split("\n")
+        explanation = []
+        in_explanation = False
+
+        for line in lines:
+            line_lower = line.lower().strip()
+            if "explanation" in line_lower or "what this does" in line_lower:
+                in_explanation = True
+                continue
+            if line.startswith("```"):
+                in_explanation = False
+                continue
+            if in_explanation:
+                explanation.append(line)
+            elif line.startswith("#") or line.startswith("//"):
+                explanation.append(line.lstrip("#/").strip())
+
+        return " ".join(explanation) if explanation else "Generated command"
+
+    def _estimate_confidence(self, response: str) -> float:
+        """Estimate confidence score based on response characteristics."""
+        confidence = 0.5
+
+        if "```" in response:
+            confidence += 0.2
+        if len(response) > 50:
+            confidence += 0.1
+        if "sure" in response.lower() or "certain" in response.lower():
+            confidence += 0.1
+        if "?" in response:
+            confidence -= 0.2
+        if "not sure" in response.lower() or "uncertain" in response.lower():
+            confidence -= 0.3
+
+        return max(0.0, min(1.0, confidence))