package ai

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// OllamaModelInfo holds detailed info about an installed Ollama model.
type OllamaModelInfo struct {
	Name       string `json:"name"`
	Size       int64  `json:"size"`
	ModifiedAt string `json:"modified_at"`
	Details    struct {
		ParameterSize     string `json:"parameter_size"`
		QuantizationLevel string `json:"quantization_level"`
		Family            string `json:"family"`
	} `json:"details"`
}

// OllamaProvider implements Provider for Ollama and also exposes model management operations.
type OllamaProvider struct {
	endpoint string
	model    string
	client   *http.Client
}

func newOllama(endpoint, model string) *OllamaProvider {
	if endpoint == "" {
		endpoint = "http://ollama:11434"
	}
	if model == "" {
		model = "llama3"
	}
	return &OllamaProvider{
		endpoint: endpoint,
		model:    model,
		client:   &http.Client{},
	}
}

// NewOllamaManager creates an OllamaProvider for model management (pull/delete/list).
func NewOllamaManager(endpoint string) *OllamaProvider {
	return newOllama(endpoint, "")
}


func (p *OllamaProvider) Name() string { return "ollama" }

func (p *OllamaProvider) Summarize(ctx context.Context, prompt string, opts GenOptions) (string, error) {
	numCtx := 32768
	if opts.NumCtx > 0 {
		numCtx = opts.NumCtx
	}
	body := map[string]interface{}{
		"model":  p.model,
		"prompt": prompt,
		"stream": false,
		"think":  opts.Think,
		"options": map[string]interface{}{
			"num_ctx": numCtx,
		},
	}
	b, _ := json.Marshal(body)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, p.endpoint+"/api/generate", bytes.NewReader(b))
	if err != nil {
		return "", err
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := p.client.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	raw, _ := io.ReadAll(resp.Body)
	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("ollama API error %d: %s", resp.StatusCode, raw)
	}

	var result struct {
		Response string `json:"response"`
	}
	if err := json.Unmarshal(raw, &result); err != nil {
		return "", err
	}
	return result.Response, nil
}

func (p *OllamaProvider) ListModels(ctx context.Context) ([]string, error) {
	infos, err := p.ListModelsDetailed(ctx)
	if err != nil {
		return nil, err
	}
	names := make([]string, len(infos))
	for i, m := range infos {
		names[i] = m.Name
	}
	return names, nil
}

func (p *OllamaProvider) ListModelsDetailed(ctx context.Context) ([]OllamaModelInfo, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, p.endpoint+"/api/tags", nil)
	if err != nil {
		return nil, err
	}
	resp, err := p.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	raw, _ := io.ReadAll(resp.Body)
	var result struct {
		Models []OllamaModelInfo `json:"models"`
	}
	if err := json.Unmarshal(raw, &result); err != nil {
		return nil, err
	}
	return result.Models, nil
}

// PullModel pulls (downloads) a model from Ollama Hub. Blocks until complete.
func (p *OllamaProvider) PullModel(ctx context.Context, name string) error {
	body, _ := json.Marshal(map[string]interface{}{"name": name, "stream": false})
	// Use a long-timeout client since model downloads can take many minutes
	client := &http.Client{Timeout: 60 * time.Minute}
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, p.endpoint+"/api/pull", bytes.NewReader(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	raw, _ := io.ReadAll(resp.Body)
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("ollama pull error %d: %s", resp.StatusCode, raw)
	}
	return nil
}

// DeleteModel removes a model from local storage.
func (p *OllamaProvider) DeleteModel(ctx context.Context, name string) error {
	body, _ := json.Marshal(map[string]string{"name": name})
	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, p.endpoint+"/api/delete", bytes.NewReader(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := p.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusNoContent {
		raw, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("ollama delete error %d: %s", resp.StatusCode, raw)
	}
	return nil
}