package main

import (
	"fmt"
	"net/url"
	"os"
	"regexp"
	"strings"
	"time"

	"sigs.k8s.io/yaml"
)

type Contribution struct {
	URLs        []string `json:"urls"`
	Tags        []string `json:"tags"`
	SponsoredBy string   `json:"sponsored-by"`
	Desc        string   `json:"desc"`

	SubmittedAt   time.Time `json:"submitted-at"`
	LastUpdatedAt time.Time `json:"last-updated-at"`
	Status        string    `json:"status"`
}

func ReadContribs(filename string) ([]Contribution, error) {
	bs, err := os.ReadFile(filename)
	if err != nil {
		return nil, fmt.Errorf("contribs: %q: %w", filename, err)
	}
	var ret []Contribution
	if err := yaml.UnmarshalStrict(bs, &ret); err != nil {
		return nil, fmt.Errorf("contribs: %q: %w", filename, err)
	}
	for i := range ret {
		contrib := ret[i]
		if err := contrib.Fill(); err != nil {
			return nil, fmt.Errorf("contribs: %q: %w", filename, err)
		}
		ret[i] = contrib
	}
	return ret, nil
}

func (c *Contribution) Fill() error {
	var err error
	if c.SubmittedAt.IsZero() {
		c.SubmittedAt, err = c.fetchSubmittedAt()
		if err != nil {
			return err
		}
	}
	if c.Status == "" {
		c.Status, err = c.fetchStatus()
		if err != nil {
			return err
		}
	}
	return nil
}

var (
	reGitHubPR      = regexp.MustCompile(`^https://github.com/([^/?#]+)/([^/?#]+)/pull/([0-9]+)(?:\?[^#]*)?(?:#.*)?$`)
	reGitLabMR      = regexp.MustCompile(`^https://([^/]+)/([^?#]+)/-/merge_requests/([0-9]+)(?:\?[^#]*)?(?:#.*)?$`)
	rePiperMailDate = regexp.MustCompile(`^\s*<I>([^<]+)</I>\s*$`)
)

func (c Contribution) fetchStatus() (string, error) {
	if m := reGitHubPR.FindStringSubmatch(c.URLs[0]); m != nil {
		user := m[1]
		repo := m[2]
		prnum := m[3]

		urlStr := "https://api.github.com/repos/" + user + "/" + repo + "/pulls/" + prnum

		var obj struct {
			State string `json:"state"`
		}
		if err := httpGetJSON(urlStr, &obj); err != nil {
			return "", err
		}
		return obj.State, nil
	}
	if m := reGitLabMR.FindStringSubmatch(c.URLs[0]); m != nil {
		authority := m[1]
		projectID := m[2]
		mrnum := m[3]

		urlStr := "https://" + authority + "/api/v4/projects/" + url.QueryEscape(projectID) + "/merge_requests/" + mrnum

		var obj struct {
			State string `json:"state"`
		}
		if err := httpGetJSON(urlStr, &obj); err != nil {
			return "", err
		}
		return obj.State, nil
	}
	if len(c.URLs) > 1 {
		for _, u := range c.URLs[1:] {
			if strings.Contains(u, "/commit/") {
				return "merged", nil
			}
		}
	}
	return "", fmt.Errorf("idk how to get status for %q", c.URLs[0])
}

func (c Contribution) fetchSubmittedAt() (time.Time, error) {
	if m := reGitHubPR.FindStringSubmatch(c.URLs[0]); m != nil {
		user := m[1]
		repo := m[2]
		prnum := m[3]

		urlStr := "https://api.github.com/repos/" + user + "/" + repo + "/pulls/" + prnum

		var obj struct {
			CreatedAt time.Time `json:"created_at"`
		}
		if err := httpGetJSON(urlStr, &obj); err != nil {
			return time.Time{}, err
		}
		return obj.CreatedAt, nil
	}
	if m := reGitLabMR.FindStringSubmatch(c.URLs[0]); m != nil {
		authority := m[1]
		projectID := m[2]
		mrnum := m[3]

		urlStr := "https://" + authority + "/api/v4/projects/" + url.QueryEscape(projectID) + "/merge_requests/" + mrnum

		var obj struct {
			CreatedAt time.Time `json:"created_at"`
		}
		if err := httpGetJSON(urlStr, &obj); err != nil {
			return time.Time{}, err
		}
		return obj.CreatedAt, nil
	}
	if strings.Contains(c.URLs[0], "/pipermail/") {
		htmlStr, err := httpGet(c.URLs[0])
		if err != nil {
			return time.Time{}, err
		}
		for _, line := range strings.Split(htmlStr, "\n") {
			if m := rePiperMailDate.FindStringSubmatch(line); m != nil {
				return time.Parse(time.UnixDate, m[1])
			}
		}
	}
	return time.Time{}, fmt.Errorf("idk how to get timestamps for %q", c.URLs[0])
}