package gitea

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"

	"gitea-codex-bot/internal/config"
	"gitea-codex-bot/internal/domain"
)

type Client struct {
	baseURL, token string
	httpClient     *http.Client
}

func NewClient(settings config.Settings) *Client {
	return &Client{baseURL: strings.TrimRight(settings.GiteaBaseURL, "/"), token: settings.GiteaToken, httpClient: &http.Client{Timeout: 20 * time.Second}}
}

func (c *Client) request(ctx context.Context, method, path string, body any) ([]byte, int, error) {
	var reader io.Reader
	if body != nil {
		data, err := json.Marshal(body)
		if err != nil {
			return nil, 0, err
		}
		reader = strings.NewReader(string(data))
	}
	req, err := http.NewRequestWithContext(ctx, method, c.baseURL+path, reader)
	if err != nil {
		return nil, 0, err
	}
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "token "+c.token)
	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, 0, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(io.LimitReader(resp.Body, 4<<20))
	if err != nil {
		return nil, resp.StatusCode, err
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return data, resp.StatusCode, fmt.Errorf("gitea returned HTTP %d", resp.StatusCode)
	}
	return data, resp.StatusCode, nil
}

func splitRepo(repo string) (string, string, error) {
	owner, name, ok := strings.Cut(repo, "/")
	if !ok || owner == "" || name == "" {
		return "", "", fmt.Errorf("invalid repository %q", repo)
	}
	return url.PathEscape(owner), url.PathEscape(name), nil
}

func (c *Client) GetPullRequest(ctx context.Context, repo string, number int) (domain.PullRequestContext, error) {
	owner, name, err := splitRepo(repo)
	if err != nil {
		return domain.PullRequestContext{}, err
	}
	data, _, err := c.request(ctx, http.MethodGet, fmt.Sprintf("/api/v1/repos/%s/%s/pulls/%d", owner, name, number), nil)
	if err != nil {
		return domain.PullRequestContext{}, err
	}
	var p struct {
		HTMLURL string `json:"html_url"`
		Base    struct {
			Ref, SHA string
			Repo     struct {
				CloneURL string `json:"clone_url"`
				FullName string `json:"full_name"`
			} `json:"repo"`
		} `json:"base"`
		Head struct {
			Ref, SHA string
			Repo     struct {
				CloneURL string `json:"clone_url"`
				FullName string `json:"full_name"`
			} `json:"repo"`
		} `json:"head"`
	}
	if err := json.Unmarshal(data, &p); err != nil {
		return domain.PullRequestContext{}, err
	}
	if p.Base.SHA == "" || p.Head.SHA == "" || p.Base.Repo.CloneURL == "" || p.Head.Repo.CloneURL == "" {
		return domain.PullRequestContext{}, fmt.Errorf("gitea pull request response missing required fields")
	}
	return domain.PullRequestContext{Repo: repo, PRNumber: number, BaseRef: p.Base.Ref, BaseSHA: p.Base.SHA, HeadRef: p.Head.Ref, HeadSHA: p.Head.SHA, CloneURL: p.Head.Repo.CloneURL, BaseCloneURL: p.Base.Repo.CloneURL, HeadCloneURL: p.Head.Repo.CloneURL, HTMLURL: p.HTMLURL, IsFork: p.Base.Repo.FullName != p.Head.Repo.FullName}, nil
}

func (c *Client) GetFileContent(ctx context.Context, repo, path, ref string) (string, bool, error) {
	owner, name, err := splitRepo(repo)
	if err != nil {
		return "", false, err
	}
	data, status, err := c.request(ctx, http.MethodGet, fmt.Sprintf("/api/v1/repos/%s/%s/contents/%s?ref=%s", owner, name, url.PathEscape(path), url.QueryEscape(ref)), nil)
	if err != nil && status == http.StatusNotFound {
		return "", false, nil
	}
	if err != nil {
		return "", false, err
	}
	var p struct {
		Content  string `json:"content"`
		Encoding string `json:"encoding"`
	}
	if err := json.Unmarshal(data, &p); err != nil {
		return "", false, err
	}
	if p.Encoding != "base64" || p.Content == "" {
		return "", false, nil
	}
	decoded, err := base64.StdEncoding.DecodeString(strings.ReplaceAll(p.Content, "\n", ""))
	if err != nil {
		return "", false, err
	}
	return string(decoded), true, nil
}

func (c *Client) PostIssueComment(ctx context.Context, repo string, number int, body string) (int64, error) {
	owner, name, err := splitRepo(repo)
	if err != nil {
		return 0, err
	}
	data, _, err := c.request(ctx, http.MethodPost, fmt.Sprintf("/api/v1/repos/%s/%s/issues/%d/comments", owner, name, number), map[string]string{"body": body})
	if err != nil {
		return 0, err
	}
	var p struct {
		ID int64 `json:"id"`
	}
	if err := json.Unmarshal(data, &p); err != nil {
		return 0, err
	}
	if p.ID <= 0 {
		return 0, fmt.Errorf("gitea comment response missing a positive id")
	}
	return p.ID, nil
}
func (c *Client) EditIssueComment(ctx context.Context, repo string, commentID int64, body string) (int64, error) {
	owner, name, err := splitRepo(repo)
	if err != nil {
		return 0, err
	}
	data, _, err := c.request(ctx, http.MethodPatch, fmt.Sprintf("/api/v1/repos/%s/%s/issues/comments/%d", owner, name, commentID), map[string]string{"body": body})
	if err != nil {
		return 0, err
	}
	var p struct {
		ID int64 `json:"id"`
	}
	if err := json.Unmarshal(data, &p); err != nil {
		return 0, err
	}
	if p.ID <= 0 {
		return 0, fmt.Errorf("gitea comment response missing a positive id")
	}
	return p.ID, nil
}
func (c *Client) GetIssueComments(ctx context.Context, repo string, number int) ([]map[string]any, error) {
	owner, name, err := splitRepo(repo)
	if err != nil {
		return nil, err
	}
	data, _, err := c.request(ctx, http.MethodGet, fmt.Sprintf("/api/v1/repos/%s/%s/issues/%d/comments", owner, name, number), nil)
	if err != nil {
		return nil, err
	}
	var p []map[string]any
	if err := json.Unmarshal(data, &p); err != nil {
		return nil, err
	}
	return p, nil
}
func (c *Client) GetIssueComment(ctx context.Context, repo string, commentID int64) (map[string]any, error) {
	owner, name, err := splitRepo(repo)
	if err != nil {
		return nil, err
	}
	data, _, err := c.request(ctx, http.MethodGet, fmt.Sprintf("/api/v1/repos/%s/%s/issues/comments/%d", owner, name, commentID), nil)
	if err != nil {
		return nil, err
	}
	var p map[string]any
	if err := json.Unmarshal(data, &p); err != nil {
		return nil, err
	}
	return p, nil
}