package client

import (
	"context"
	"fmt"
	"io"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"somegit.dev/vikingowl/reddit-reader/internal/domain"
	pb "somegit.dev/vikingowl/reddit-reader/proto/redditreader"
)

// Client wraps a gRPC connection to the RedditReader service.
type Client struct {
	conn   *grpc.ClientConn
	client pb.RedditReaderClient
}

// Dial connects to the gRPC server via a Unix socket.
func Dial(socketPath string) (*Client, error) {
	conn, err := grpc.NewClient(
		"unix://"+socketPath,
		grpc.WithTransportCredentials(insecure.NewCredentials()),
	)
	if err != nil {
		return nil, fmt.Errorf("grpc dial: %w", err)
	}
	return &Client{
		conn:   conn,
		client: pb.NewRedditReaderClient(conn),
	}, nil
}

// Close closes the underlying gRPC connection.
func (c *Client) Close() error {
	return c.conn.Close()
}

// ListPosts retrieves posts matching the given subreddit and limit.
func (c *Client) ListPosts(ctx context.Context, subreddit string, limit int) ([]domain.Post, error) {
	resp, err := c.client.ListPosts(ctx, &pb.ListRequest{
		Subreddit: subreddit,
		Limit:     int32(limit),
	})
	if err != nil {
		return nil, fmt.Errorf("list posts: %w", err)
	}
	posts := make([]domain.Post, len(resp.GetPosts()))
	for i, p := range resp.GetPosts() {
		posts[i] = protoToDomain(p)
	}
	return posts, nil
}

// UpdatePost updates flags on a post and returns the updated version.
func (c *Client) UpdatePost(ctx context.Context, id string, read, starred, dismissed *bool) (domain.Post, error) {
	req := &pb.UpdateRequest{Id: id}
	if read != nil {
		req.Read = read
	}
	if starred != nil {
		req.Starred = starred
	}
	if dismissed != nil {
		req.Dismissed = dismissed
	}
	resp, err := c.client.UpdatePost(ctx, req)
	if err != nil {
		return domain.Post{}, fmt.Errorf("update post: %w", err)
	}
	return protoToDomain(resp), nil
}

// SubmitFeedback records a vote for a post.
func (c *Client) SubmitFeedback(ctx context.Context, postID string, vote int) error {
	_, err := c.client.SubmitFeedback(ctx, &pb.FeedbackRequest{
		PostId: postID,
		Vote:   int32(vote),
	})
	if err != nil {
		return fmt.Errorf("submit feedback: %w", err)
	}
	return nil
}

// ListSubreddits returns all configured subreddits.
func (c *Client) ListSubreddits(ctx context.Context) ([]domain.Subreddit, error) {
	resp, err := c.client.ListSubreddits(ctx, &pb.Empty{})
	if err != nil {
		return nil, fmt.Errorf("list subreddits: %w", err)
	}
	subs := make([]domain.Subreddit, len(resp.GetSubreddits()))
	for i, s := range resp.GetSubreddits() {
		subs[i] = domain.Subreddit{
			Name:     s.GetName(),
			Enabled:  s.GetEnabled(),
			PollSort: s.GetPollSort(),
		}
	}
	return subs, nil
}

// AddSubreddit adds a subreddit with the given sort order.
func (c *Client) AddSubreddit(ctx context.Context, name, sort string) error {
	_, err := c.client.AddSubreddit(ctx, &pb.AddSubredditRequest{
		Name:     name,
		PollSort: sort,
	})
	if err != nil {
		return fmt.Errorf("add subreddit: %w", err)
	}
	return nil
}

// RemoveSubreddit deletes a subreddit by name.
func (c *Client) RemoveSubreddit(ctx context.Context, name string) error {
	_, err := c.client.RemoveSubreddit(ctx, &pb.RemoveRequest{Name: name})
	if err != nil {
		return fmt.Errorf("remove subreddit: %w", err)
	}
	return nil
}

// StreamPosts returns a channel that receives posts as they are pushed by the server.
func (c *Client) StreamPosts(ctx context.Context) (<-chan domain.Post, error) {
	stream, err := c.client.StreamPosts(ctx, &pb.StreamRequest{})
	if err != nil {
		return nil, fmt.Errorf("stream posts: %w", err)
	}
	ch := make(chan domain.Post, 64)
	go func() {
		defer close(ch)
		for {
			p, err := stream.Recv()
			if err == io.EOF {
				return
			}
			if err != nil {
				return
			}
			select {
			case ch <- protoToDomain(p):
			case <-ctx.Done():
				return
			}
		}
	}()
	return ch, nil
}

// Status returns the server's status information.
func (c *Client) Status(ctx context.Context) (*pb.StatusResponse, error) {
	resp, err := c.client.Status(ctx, &pb.Empty{})
	if err != nil {
		return nil, fmt.Errorf("status: %w", err)
	}
	return resp, nil
}

func protoToDomain(p *pb.Post) domain.Post {
	post := domain.Post{
		ID:        p.GetId(),
		Subreddit: p.GetSubreddit(),
		Title:     p.GetTitle(),
		Author:    p.GetAuthor(),
		URL:       p.GetUrl(),
		SelfText:  p.GetSelfText(),
		Score:     int(p.GetScore()),
		Read:      p.GetRead(),
		Starred:   p.GetStarred(),
		Dismissed: p.GetDismissed(),
	}
	if ts := p.GetCreatedUtc(); ts != nil {
		post.CreatedUTC = ts.AsTime()
	}
	if ts := p.GetFetchedAt(); ts != nil {
		post.FetchedAt = ts.AsTime()
	}
	if p.Relevance != nil {
		v := p.GetRelevance()
		post.Relevance = &v
	}
	if p.Summary != nil {
		v := p.GetSummary()
		post.Summary = &v
	}
	return post
}