package llm

import (
    "context"
    "fmt"
    "net/url"
    "os"

    ollamaapi "github.com/ollama/ollama/api"
)

// OllamaClient implements Client using the official Ollama Go library.
type OllamaClient struct {
    client *ollamaapi.Client
    model  string
    numCtx int
}

// NewOllamaClient creates a new Ollama client.
func NewOllamaClient(baseURL, model string, numCtx int) (*OllamaClient, error) {
    // The official client reads OLLAMA_HOST, but we want to support our config too.
    if baseURL != "" {
        os.Setenv("OLLAMA_HOST", baseURL)
    }

    client, err := ollamaapi.ClientFromEnvironment()
    if err != nil {
        return nil, fmt.Errorf("create ollama client: %w", err)
    }

    return &OllamaClient{
        client: client,
        model:  model,
        numCtx: numCtx,
    }, nil
}

func (o *OllamaClient) Model() string { return o.model }

// Ping checks Ollama is running and the model exists.
func (o *OllamaClient) Ping() error {
    ctx := context.Background()

    // Check the model is available by requesting a show.
    req := &ollamaapi.ShowRequest{Model: o.model}
    _, err := o.client.Show(ctx, req)
    if err != nil {
        return fmt.Errorf("model %q not available: %w", o.model, err)
    }
    return nil
}

// ChatStream sends a chat request and streams the response via callback.
func (o *OllamaClient) ChatStream(ctx context.Context, opts ChatOptions, fn func(StreamChunk) error) error {

    messages := make([]ollamaapi.Message, 0, len(opts.Messages)+1)
    if opts.System != "" {
        messages = append(messages, ollamaapi.Message{
            Role:    "system",
            Content: opts.System,
        })
    }
    for _, m := range opts.Messages {
        msg := ollamaapi.Message{
            Role:       m.Role,
            Content:    m.Content,
            ToolName:   m.ToolName,
            ToolCallID: m.ToolCallID,
        }
        // Convert tool calls for assistant messages.
        for _, tc := range m.ToolCalls {
            args := ollamaapi.NewToolCallFunctionArguments()
            for k, v := range tc.Arguments {
                args.Set(k, v)
            }
            msg.ToolCalls = append(msg.ToolCalls, ollamaapi.ToolCall{
                ID: tc.ID,
                Function: ollamaapi.ToolCallFunction{
                    Name:      tc.Name,
                    Arguments: args,
                },
            })
        }
        messages = append(messages, msg)
    }

    tools := convertTools(opts.Tools)
    req := &ollamaapi.ChatRequest{
        Model:    o.model,
        Messages: messages,
        Tools:    tools,
        Options: map[string]any{
            "num_ctx": o.numCtx,
        },
    }

    return o.client.Chat(ctx, req, func(resp ollamaapi.ChatResponse) error {
        chunk := StreamChunk{
            Text: resp.Message.Content,
            Done: resp.Done,
        }
        if resp.Done {
            chunk.EvalCount = resp.EvalCount
            chunk.PromptEvalCount = resp.PromptEvalCount
        }
        // Collect tool calls from the response.
        for _, tc := range resp.Message.ToolCalls {
            chunk.ToolCalls = append(chunk.ToolCalls, ToolCall{
                ID:        tc.ID,
                Name:      tc.Function.Name,
                Arguments: tc.Function.Arguments.ToMap(),
            })
        }
        return fn(chunk)
    })
}

// Embed generates embeddings for the given texts using the specified model.
func (o *OllamaClient) Embed(ctx context.Context, model string, texts []string) ([][]float32, error) {
    resp, err := o.client.Embed(ctx, &ollamaapi.EmbedRequest{
        Model: model,
        Input: texts,
    })
    if err != nil {
        return nil, fmt.Errorf("embedding failed: %w", err)
    }
    return resp.Embeddings, nil
}

// convertTools transforms our ToolDef slice into Ollama's Tools format.
func convertTools(defs []ToolDef) ollamaapi.Tools {
    if len(defs) == 0 {
        return nil
    }

    tools := make(ollamaapi.Tools, 0, len(defs))
    for _, d := range defs {
        props := ollamaapi.NewToolPropertiesMap()
        var required []string

        // Extract properties from JSON Schema.
        if propsRaw, ok := d.Parameters["properties"].(map[string]any); ok {
            for name, schema := range propsRaw {
                schemaMap, _ := schema.(map[string]any)
                prop := ollamaapi.ToolProperty{
                    Description: strFromMap(schemaMap, "description"),
                }
                if t, ok := schemaMap["type"].(string); ok {
                    prop.Type = ollamaapi.PropertyType{t}
                }
                if enumRaw, ok := schemaMap["enum"].([]any); ok {
                    prop.Enum = enumRaw
                }
                props.Set(name, prop)
            }
        }

        // Extract required fields.
        if reqRaw, ok := d.Parameters["required"].([]any); ok {
            for _, r := range reqRaw {
                if s, ok := r.(string); ok {
                    required = append(required, s)
                }
            }
        }

        tools = append(tools, ollamaapi.Tool{
            Type: "function",
            Function: ollamaapi.ToolFunction{
                Name:        d.Name,
                Description: d.Description,
                Parameters: ollamaapi.ToolFunctionParameters{
                    Type:       "object",
                    Properties: props,
                    Required:   required,
                },
            },
        })
    }
    return tools
}

func strFromMap(m map[string]any, key string) string {
    if m == nil {
        return ""
    }
    s, _ := m[key].(string)
    return s
}

// BaseURL returns the configured Ollama base URL for display.
func (o *OllamaClient) BaseURL() string {
    if v := os.Getenv("OLLAMA_HOST"); v != "" {
        return v
    }
    return "http://localhost:11434"
}

// ParseBaseURL validates the Ollama URL.
func ParseBaseURL(rawURL string) (*url.URL, error) {
    return url.Parse(rawURL)
}

// ListModels returns model names available in Ollama at baseURL.
func ListModels(ctx context.Context, baseURL string) ([]string, error) {
    if baseURL != "" {
        os.Setenv("OLLAMA_HOST", baseURL)
    }
    client, err := ollamaapi.ClientFromEnvironment()
    if err != nil {
        return nil, fmt.Errorf("ollama client: %w", err)
    }
    resp, err := client.List(ctx)
    if err != nil {
        return nil, fmt.Errorf("ollama list: %w", err)
    }
    names := make([]string, 0, len(resp.Models))
    for _, m := range resp.Models {
        names = append(names, m.Name)
    }
    return names, nil
}