// Package gitea implements capture.IssueTracker against a Gitea instance
// over its REST API. It is the new outbound dependency the brain server
// gains for the capture capability (#49c/#52): the server otherwise does
// brain-local file ops only.
//
// Owner is hard-coded to the operator and never taken from caller input.
// The API token is read once at construction, held in the struct, and
// never logged or placed in argv — it travels only in the Authorization
// header of outbound requests (AGENTS.md secret-handling).
package gitea

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

	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
)

// owner is the fixed repository owner for every ticket operation. It is a
// constant, not a parameter, so a caller can never redirect a write to
// another owner's repo.
const owner = "mathias"

// Client is a Gitea REST API IssueTracker.
type Client struct {
	baseURL string
	token   string
	http    *http.Client
}

// New constructs a Client. It returns nil when either baseURL or token is
// empty, so callers can treat missing config as "tracker disabled" with a
// single nil check (mirrors embed.New).
func New(baseURL, token string) *Client {
	if baseURL == "" || token == "" {
		return nil
	}
	return &Client{
		baseURL: strings.TrimRight(baseURL, "/"),
		token:   token,
		http:    &http.Client{Timeout: 15 * time.Second},
	}
}

// issueResponse is the subset of a Gitea issue/comment payload we read.
type issueResponse struct {
	Number  int    `json:"number"`
	HTMLURL string `json:"html_url"`
}

// CreateIssue opens a new issue under the fixed owner.
func (c *Client) CreateIssue(ctx context.Context, repo, title, body string) (capture.IssueRef, error) {
	var out issueResponse
	if err := c.do(ctx, http.MethodPost,
		fmt.Sprintf("/api/v1/repos/%s/%s/issues", owner, repo),
		map[string]any{"title": title, "body": body}, &out); err != nil {
		return capture.IssueRef{}, err
	}
	return capture.IssueRef{Repo: repo, Number: out.Number, URL: out.HTMLURL}, nil
}

// CommentIssue posts a comment on an existing issue.
func (c *Client) CommentIssue(ctx context.Context, repo string, number int, body string) (capture.IssueRef, error) {
	var out issueResponse
	if err := c.do(ctx, http.MethodPost,
		fmt.Sprintf("/api/v1/repos/%s/%s/issues/%d/comments", owner, repo, number),
		map[string]any{"body": body}, &out); err != nil {
		return capture.IssueRef{}, err
	}
	return capture.IssueRef{Repo: repo, Number: number, URL: out.HTMLURL}, nil
}

// CloseIssue closes an issue, first posting a closing comment when one is
// given (empty comment ⇒ close only).
func (c *Client) CloseIssue(ctx context.Context, repo string, number int, comment string) (capture.IssueRef, error) {
	if strings.TrimSpace(comment) != "" {
		if _, err := c.CommentIssue(ctx, repo, number, comment); err != nil {
			return capture.IssueRef{}, err
		}
	}
	var out issueResponse
	if err := c.do(ctx, http.MethodPatch,
		fmt.Sprintf("/api/v1/repos/%s/%s/issues/%d", owner, repo, number),
		map[string]any{"state": "closed"}, &out); err != nil {
		return capture.IssueRef{}, err
	}
	return capture.IssueRef{Repo: repo, Number: number, URL: out.HTMLURL}, nil
}

// do performs a JSON request against the Gitea API and decodes the
// response into out. Errors carry the status and a truncated body for
// diagnosis but never the token.
func (c *Client) do(ctx context.Context, method, path string, payload any, out *issueResponse) error {
	reqBody, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshal request: %w", err)
	}
	req, err := http.NewRequestWithContext(ctx, method, c.baseURL+path, bytes.NewReader(reqBody))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")
	// Gitea's token scheme. Held here only; never logged.
	req.Header.Set("Authorization", "token "+c.token)

	resp, err := c.http.Do(req)
	if err != nil {
		return fmt.Errorf("gitea %s %s: %w", method, path, err)
	}
	defer func() { _ = resp.Body.Close() }()

	respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("gitea %s %s: status %d: %s", method, path, resp.StatusCode, strings.TrimSpace(string(respBody)))
	}
	if out != nil && len(respBody) > 0 {
		if err := json.Unmarshal(respBody, out); err != nil {
			return fmt.Errorf("gitea %s %s: decode response: %w", method, path, err)
		}
	}
	return nil
}