package gitea

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

// Repo represents a Gitea repository.
type Repo struct {
	Name          string `json:"name"`
	Description   string `json:"description"`
	DefaultBranch string `json:"default_branch"`
}

// TreeEntry represents a file in a Gitea repo tree.
type TreeEntry struct {
	Path string `json:"path"`
	Type string `json:"type"` // "blob" or "tree"
}

// TreeResponse is the Gitea API response for a recursive tree listing.
type TreeResponse struct {
	Tree []TreeEntry `json:"tree"`
}

// CommitMeta holds minimal commit info for a file.
type CommitMeta struct {
	SHA  string    `json:"sha"`
	Date time.Time `json:"-"`
}

// RepoCommit is used to extract the latest commit SHA for a repo.
type RepoCommit struct {
	SHA    string         `json:"sha"`
	Commit repoCommitInfo `json:"commit"`
}

type repoCommitInfo struct {
	Committer commitPerson `json:"committer"`
}

type commitPerson struct {
	Date time.Time `json:"date"`
}

// Client fetches content from a Gitea instance.
type Client struct {
	baseURL    string
	org        string
	httpClient *http.Client
}

// NewClient creates a Gitea API client.
func NewClient(baseURL, org string, timeout time.Duration) *Client {
	return &Client{
		baseURL: strings.TrimRight(baseURL, "/"),
		org:     org,
		httpClient: &http.Client{
			Timeout: timeout,
		},
	}
}

// ListRepos returns all repositories in the configured organization.
func (c *Client) ListRepos(ctx context.Context) ([]Repo, error) {
	var allRepos []Repo
	page := 1

	for {
		url := fmt.Sprintf("%s/api/v1/orgs/%s/repos?page=%d&limit=50", c.baseURL, c.org, page)
		var repos []Repo
		if err := c.getJSON(ctx, url, &repos); err != nil {
			return nil, fmt.Errorf("list repos page %d: %w", page, err)
		}
		if len(repos) == 0 {
			break
		}
		allRepos = append(allRepos, repos...)
		page++
	}

	return allRepos, nil
}

// ListMarkdownFiles returns paths to all .md files in a repo's default branch.
func (c *Client) ListMarkdownFiles(ctx context.Context, repo, branch string) ([]string, error) {
	url := fmt.Sprintf("%s/api/v1/repos/%s/%s/git/trees/%s?recursive=true",
		c.baseURL, c.org, repo, branch)

	var tree TreeResponse
	if err := c.getJSON(ctx, url, &tree); err != nil {
		return nil, fmt.Errorf("list tree for %s: %w", repo, err)
	}

	var files []string
	for _, entry := range tree.Tree {
		if entry.Type == "blob" && strings.HasSuffix(strings.ToLower(entry.Path), ".md") {
			files = append(files, entry.Path)
		}
	}
	return files, nil
}

// FetchFileContent returns the raw content of a file in a repo.
func (c *Client) FetchFileContent(ctx context.Context, repo, branch, filepath string) ([]byte, error) {
	url := fmt.Sprintf("%s/api/v1/repos/%s/%s/raw/%s?ref=%s",
		c.baseURL, c.org, repo, filepath, branch)
	return c.getRaw(ctx, url)
}

// LatestCommitSHA returns the SHA of the latest commit on a branch.
func (c *Client) LatestCommitSHA(ctx context.Context, repo, branch string) (string, time.Time, error) {
	url := fmt.Sprintf("%s/api/v1/repos/%s/%s/commits?sha=%s&limit=1",
		c.baseURL, c.org, repo, branch)

	var commits []RepoCommit
	if err := c.getJSON(ctx, url, &commits); err != nil {
		return "", time.Time{}, fmt.Errorf("latest commit for %s: %w", repo, err)
	}
	if len(commits) == 0 {
		return "", time.Time{}, fmt.Errorf("no commits found for %s/%s", repo, branch)
	}

	return commits[0].SHA, commits[0].Commit.Committer.Date, nil
}

func (c *Client) getJSON(ctx context.Context, url string, target interface{}) error {
	body, err := c.getRaw(ctx, url)
	if err != nil {
		return err
	}
	return json.Unmarshal(body, target)
}

func (c *Client) getRaw(ctx context.Context, url string) ([]byte, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, fmt.Errorf("create request: %w", err)
	}

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

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("fetch %s: status %d", url, resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("read response from %s: %w", url, err)
	}
	return body, nil
}