package gollama

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

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

// Client wraps the official Ollama API client with ergonomic defaults.
type Client struct {
	api          *api.Client
	host         *url.URL
	defaultModel string
	defaultOpts  OptionSet
}

// ClientOption configures a Client.
type ClientOption func(*Client)

// WithDefaultModel sets the model used when calls do not specify one.
func WithDefaultModel(name string) ClientOption {
	return func(c *Client) { c.defaultModel = name }
}

// WithDefaultOptions sets client-wide generation options.
func WithDefaultOptions(opts OptionSet) ClientOption {
	return func(c *Client) { c.defaultOpts = opts }
}

// WithHTTPClient sets the HTTP client used for API requests.
func WithHTTPClient(httpClient *http.Client) ClientOption {
	return func(c *Client) {
		if httpClient != nil && c.host != nil {
			c.api = api.NewClient(c.host, httpClient)
		}
	}
}

// FromEnv creates a Client using OLLAMA_HOST (default http://127.0.0.1:11434).
func FromEnv(opts ...ClientOption) (*Client, error) {
	apiClient, err := api.ClientFromEnvironment()
	if err != nil {
		return nil, wrapError("connect", "", err)
	}
	c := newClient(apiClient, nil, opts...)
	// Re-read host from env for WithHTTPClient; api.ClientFromEnvironment uses envconfig.Host().
	if u, err := url.Parse(hostFromEnv()); err == nil {
		c.host = u
	}
	return c, nil
}

// New creates a Client for the given Ollama host URL.
func New(host string, opts ...ClientOption) (*Client, error) {
	u, err := url.Parse(host)
	if err != nil {
		return nil, wrapError("connect", "", fmt.Errorf("invalid host %q: %w", host, err))
	}
	apiClient := api.NewClient(u, http.DefaultClient)
	return newClient(apiClient, u, opts...), nil
}

func newClient(apiClient *api.Client, host *url.URL, opts ...ClientOption) *Client {
	c := &Client{api: apiClient, host: host}
	for _, opt := range opts {
		opt(c)
	}
	return c
}

func hostFromEnv() string {
	if v := os.Getenv("OLLAMA_HOST"); v != "" {
		return v
	}
	return "http://127.0.0.1:11434"
}

// Ping checks whether the Ollama server is reachable.
func (c *Client) Ping(ctx context.Context) error {
	return wrapError("ping", "", c.api.Heartbeat(ctx))
}

// DefaultModel returns the client's default model name.
func (c *Client) DefaultModel() string { return c.defaultModel }

// API returns the underlying official api.Client for advanced use.
func (c *Client) API() *api.Client { return c.api }

func (c *Client) resolveModel(model string) (string, error) {
	if model != "" {
		return model, nil
	}
	if c.defaultModel != "" {
		return c.defaultModel, nil
	}
	return "", errNoModel()
}