// 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/base64"
	"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
}

// WriteFile creates or updates a file in repo at path via the Gitea
// contents API — the SummaryWriter port (#66). It upserts: a GET resolves
// the current blob sha (if any) so an existing file is updated rather than
// rejected (the richer-fidelity-supersedes rule for re-captured sessions).
// Owner is the fixed const, like every other call.
func (c *Client) WriteFile(ctx context.Context, repo, path, content string) error {
	cpath := fmt.Sprintf("/api/v1/repos/%s/%s/contents/%s", owner, repo, path)
	sha, err := c.fileSHA(ctx, cpath)
	if err != nil {
		return err
	}
	payload := map[string]any{
		"message": "capture: " + path,
		"content": base64.StdEncoding.EncodeToString([]byte(content)),
	}
	if sha != "" {
		payload["sha"] = sha // update in place
	}
	status, body, err := c.request(ctx, http.MethodPut, cpath, payload)
	if err != nil {
		return err
	}
	if status < 200 || status >= 300 {
		return fmt.Errorf("gitea PUT %s: status %d: %s", cpath, status, strings.TrimSpace(string(body)))
	}
	return nil
}

// fileSHA returns the current blob sha for a contents path, or "" when the
// file does not exist (404). Any other non-2xx is an error.
func (c *Client) fileSHA(ctx context.Context, cpath string) (string, error) {
	status, body, err := c.request(ctx, http.MethodGet, cpath, nil)
	if err != nil {
		return "", err
	}
	if status == http.StatusNotFound {
		return "", nil
	}
	if status < 200 || status >= 300 {
		return "", fmt.Errorf("gitea GET %s: status %d: %s", cpath, status, strings.TrimSpace(string(body)))
	}
	var meta struct {
		SHA string `json:"sha"`
	}
	if err := json.Unmarshal(body, &meta); err != nil {
		return "", fmt.Errorf("gitea GET %s: decode: %w", cpath, err)
	}
	return meta.SHA, nil
}

// do performs a JSON request against the Gitea API and decodes a 2xx
// 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 {
	status, body, err := c.request(ctx, method, path, payload)
	if err != nil {
		return err
	}
	if status < 200 || status >= 300 {
		return fmt.Errorf("gitea %s %s: status %d: %s", method, path, status, strings.TrimSpace(string(body)))
	}
	if out != nil && len(body) > 0 {
		if err := json.Unmarshal(body, out); err != nil {
			return fmt.Errorf("gitea %s %s: decode response: %w", method, path, err)
		}
	}
	return nil
}

// request is the shared HTTP path: marshals an optional JSON payload,
// attaches auth (token only ever in the header), and returns the status +
// body so callers can branch on status (e.g. 404) without it being an
// error. Never logs the token.
func (c *Client) request(ctx context.Context, method, path string, payload any) (int, []byte, error) {
	var reader io.Reader
	if payload != nil {
		reqBody, err := json.Marshal(payload)
		if err != nil {
			return 0, nil, fmt.Errorf("marshal request: %w", err)
		}
		reader = bytes.NewReader(reqBody)
	}
	req, err := http.NewRequestWithContext(ctx, method, c.baseURL+path, reader)
	if err != nil {
		return 0, nil, err
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Authorization", "token "+c.token)

	resp, err := c.http.Do(req)
	if err != nil {
		return 0, nil, fmt.Errorf("gitea %s %s: %w", method, path, err)
	}
	defer func() { _ = resp.Body.Close() }()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 8192))
	return resp.StatusCode, body, nil
}