Implement Github client

Added "version control client" interface and created a Github
implementation of it. Right now it only creates pull requests and lists
issues.

Restructued some code. Idk if it will be permanent.

Next I plan to add behavior around replacing files in the local repo,
and creating commits.

pullpal/common.go

@@ -1,9 +1,11 @@
 package pullpal
 
 import (
-	"bytes"
-	"strings"
-	"text/template"
+	"context"
+
+	"github.com/mobyvb/pull-pal/vc"
+
+	"go.uber.org/zap"
 )
 
 // PullPal is the service responsible for:
@@ -12,104 +14,22 @@ import (
 //  * Parsing LLM responses
 //  * Interacting with LLM (e.g. with GPT via OpenAI API)
 type PullPal struct {
+	ctx context.Context
+	log *zap.Logger
+
+	vcClient vc.VCClient
 }
 
-// File represents a file in a git repository.
-type File struct {
-	Path     string
-	Contents string
-}
-
-// CodeChangeRequest contains all necessary information for generating a prompt for a LLM.
-type CodeChangeRequest struct {
-	Files   []File
-	Subject string
-	Body    string
-}
-
-// String is the string representation of a CodeChangeRequest. Functionally, it contains the LLM prompt.
-func (req CodeChangeRequest) String() string {
-	prompt := req.MustGetPrompt()
-	return "START OF PROMPT\n" + prompt + "\nEND OF PROMPT"
-}
-
-// MustGetPrompt only returns the prompt, but panics if the data in the request cannot populate the template.
-func (req CodeChangeRequest) MustGetPrompt() string {
-	prompt, err := req.GetPrompt()
+func NewPullPal(ctx context.Context, log *zap.Logger, self vc.Author, repo vc.Repository) (*PullPal, error) {
+	ghClient, err := vc.NewGithubClient(ctx, log, self, repo)
 	if err != nil {
-		panic(err)
-	}
-	return prompt
-}
-
-// GetPrompt converts the information in the request to a prompt for an LLM.
-func (req CodeChangeRequest) GetPrompt() (string, error) {
-	tmpl, err := template.ParseFiles("../template/code-change-request.tmpl")
-	if err != nil {
-		return "", err
+		log.Error("Failed to setup Github client.", zap.Error(err))
 	}
 
-	var result bytes.Buffer
-	err = tmpl.Execute(&result, req)
-	if err != nil {
-		return "", err
-	}
+	return &PullPal{
+		ctx: ctx,
+		log: log,
 
-	return result.String(), nil
-}
-
-// CodeChangeResponse contains data derived from an LLM response to a prompt generated via a CodeChangeRequest.
-type CodeChangeResponse struct {
-	Files []File
-	Notes string
-}
-
-// String is a string representation of CodeChangeResponse.
-func (res CodeChangeResponse) String() string {
-	out := "Notes:\n"
-	out += res.Notes + "\n\n"
-	out += "Files:\n"
-	for _, f := range res.Files {
-		out += f.Path + ":\n```\n"
-		out += f.Contents + "\n```\n"
-	}
-
-	return out
-}
-
-// ParseCodeChangeResponse parses the LLM's response to CodeChangeRequest (string) into a CodeChangeResponse.
-func ParseCodeChangeResponse(llmResponse string) CodeChangeResponse {
-	sections := strings.Split(llmResponse, "Notes:")
-
-	filesSection := sections[0]
-	notes := strings.TrimSpace(sections[1])
-
-	files := parseFiles(filesSection)
-
-	return CodeChangeResponse{
-		Files: files,
-		Notes: notes,
-	}
-}
-
-// parseFiles process the "files" subsection of the LLM's response. It is a helper for GetCodeChangeResponse.
-func parseFiles(filesSection string) []File {
-	fileStringList := strings.Split(filesSection, "name:")
-	// first item in the list is just gonna be "Files:"
-	fileStringList = fileStringList[1:]
-
-	fileList := make([]File, len(fileStringList))
-	for i, f := range fileStringList {
-		fileParts := strings.Split(f, "contents:")
-		path := strings.TrimSpace(fileParts[0])
-		contents := strings.TrimSpace(fileParts[1])
-		contents = strings.Trim(contents, "```")
-
-		fileList[i] = File{
-			Path:     path,
-			Contents: contents,
-		}
-	}
-
-	return fileList
+		vcClient: ghClient,
+	}, nil
 }