Large refactor - it compiles!

This refactor splits out all conversation concerns into a new
`conversation` package. There is now a split between `conversation` and
`api`s representation of `Message`, the latter storing the minimum
information required for interaction with LLM providers. There is
necessary conversation between the two when making LLM calls.

pkg/provider/ollama/ollama.go

@@ -0,0 +1,183 @@
+package ollama
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"git.mlow.ca/mlow/lmcli/pkg/api"
+	"git.mlow.ca/mlow/lmcli/pkg/provider"
+)
+
+type OllamaClient struct {
+	BaseURL string
+}
+
+type OllamaMessage struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
+type OllamaRequest struct {
+	Model    string          `json:"model"`
+	Messages []OllamaMessage `json:"messages"`
+	Stream   bool            `json:"stream"`
+}
+
+type OllamaResponse struct {
+	Model              string        `json:"model"`
+	CreatedAt          string        `json:"created_at"`
+	Message            OllamaMessage `json:"message"`
+	Done               bool          `json:"done"`
+	TotalDuration      uint64        `json:"total_duration,omitempty"`
+	LoadDuration       uint64        `json:"load_duration,omitempty"`
+	PromptEvalCount    uint64        `json:"prompt_eval_count,omitempty"`
+	PromptEvalDuration uint64        `json:"prompt_eval_duration,omitempty"`
+	EvalCount          uint64        `json:"eval_count,omitempty"`
+	EvalDuration       uint64        `json:"eval_duration,omitempty"`
+}
+
+func createOllamaRequest(
+	params provider.RequestParameters,
+	messages []api.Message,
+) OllamaRequest {
+	requestMessages := make([]OllamaMessage, 0, len(messages))
+
+	for _, m := range messages {
+		message := OllamaMessage{
+			Role:    string(m.Role),
+			Content: m.Content,
+		}
+		requestMessages = append(requestMessages, message)
+	}
+
+	request := OllamaRequest{
+		Model:    params.Model,
+		Messages: requestMessages,
+	}
+
+	return request
+}
+
+func (c *OllamaClient) sendRequest(req *http.Request) (*http.Response, error) {
+	req.Header.Set("Content-Type", "application/json")
+
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != 200 {
+		bytes, _ := io.ReadAll(resp.Body)
+		return resp, fmt.Errorf("%v", string(bytes))
+	}
+
+	return resp, nil
+}
+
+func (c *OllamaClient) CreateChatCompletion(
+	ctx context.Context,
+	params provider.RequestParameters,
+	messages []api.Message,
+) (*api.Message, error) {
+	if len(messages) == 0 {
+		return nil, fmt.Errorf("Can't create completion from no messages")
+	}
+
+	req := createOllamaRequest(params, messages)
+	req.Stream = false
+
+	jsonData, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+
+	httpReq, err := http.NewRequestWithContext(ctx, "POST", c.BaseURL+"/chat", bytes.NewBuffer(jsonData))
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.sendRequest(httpReq)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var completionResp OllamaResponse
+	err = json.NewDecoder(resp.Body).Decode(&completionResp)
+	if err != nil {
+		return nil, err
+	}
+
+	return api.NewMessageWithAssistant(completionResp.Message.Content), nil
+}
+
+func (c *OllamaClient) CreateChatCompletionStream(
+	ctx context.Context,
+	params provider.RequestParameters,
+	messages []api.Message,
+	output chan<- provider.Chunk,
+) (*api.Message, error) {
+	if len(messages) == 0 {
+		return nil, fmt.Errorf("Can't create completion from no messages")
+	}
+
+	req := createOllamaRequest(params, messages)
+	req.Stream = true
+
+	jsonData, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+
+	httpReq, err := http.NewRequestWithContext(ctx, "POST", c.BaseURL+"/chat", bytes.NewBuffer(jsonData))
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.sendRequest(httpReq)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	content := strings.Builder{}
+
+	reader := bufio.NewReader(resp.Body)
+	for {
+		line, err := reader.ReadBytes('\n')
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+
+		line = bytes.TrimSpace(line)
+		if len(line) == 0 {
+			continue
+		}
+
+		var streamResp OllamaResponse
+		err = json.Unmarshal(line, &streamResp)
+		if err != nil {
+			return nil, err
+		}
+
+		if len(streamResp.Message.Content) > 0 {
+			output <- provider.Chunk{
+				Content:    streamResp.Message.Content,
+				TokenCount: 1,
+			}
+			content.WriteString(streamResp.Message.Content)
+		}
+	}
+
+	return api.NewMessageWithAssistant(content.String()), nil
+}