package main

import (
	"encoding/json"
	"fmt"
	"math"
	"net/http"
	"os"
	"time"
)

type CommitsResponse struct {
	Contestant1RequiredCommits float64 `json:"contestant_1_required_commits"`
}

// Function to fetch the user's commit count
func getCommitCount(username string) (int, error) {
	currentYear := time.Now().Year()
	url := fmt.Sprintf("https://api.github.com/search/commits?q=author:%s+committer-date:%d-01-01..%d-12-31", username, currentYear, currentYear)

	// Retrieve the GitHub token from environment variables
	githubToken := os.Getenv("GITHUB_TOKEN")
	if githubToken == "" {
		return 0, fmt.Errorf("GITHUB_TOKEN environment variable is not set")
	}

	// Create a new HTTP request
	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		return 0, err
	}

	// Add necessary headers
	req.Header.Add("Accept", "application/vnd.github.cloak-preview")
	req.Header.Add("Authorization", "Bearer "+githubToken)

	// Perform the request
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return 0, err
	}
	defer resp.Body.Close()

	// Check if the response status code is 200 OK
	if resp.StatusCode != http.StatusOK {
		return 0, fmt.Errorf("GitHub API returned status: %s", resp.Status)
	}

	// Parse the response body
	var result struct {
		TotalCount int `json:"total_count"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return 0, err
	}

	return result.TotalCount, nil
}

// Calculate remaining days in the year
func daysUntilYearEnd() int {
	today := time.Now()
	endOfYear := time.Date(today.Year(), 12, 31, 23, 59, 59, 0, today.Location())
	return int(endOfYear.Sub(today).Hours() / 24)
}

// Calculate required commits per day
func calculateRequiredCommits(commits1, commits2 int, remainingDays int) (float64) {
	expectedCommits2 := float64(commits2) + float64(remainingDays)

	diffForContestant1 := math.Max(expectedCommits2-float64(commits1), 0)

	requiredCommitsPerDay1 := diffForContestant1 / float64(remainingDays)

	return requiredCommitsPerDay1 
}

// HTTP handler for the API
func calculateCommitsHandler(w http.ResponseWriter, r *http.Request) {

	// Get commit counts for both contestants
	commits1, err := getCommitCount("user1") // Replace with Contestant 1's GitHub username
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to fetch commits for Contestant 1: %s", err), http.StatusInternalServerError)
		return
	}

	commits2, err := getCommitCount("user2") // Replace with Contestant 2's GitHub username
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to fetch commits for Contestant 2: %s", err), http.StatusInternalServerError)
		return
	}

	// Calculate required commits
	remainingDays := daysUntilYearEnd()
	requiredCommits1 := calculateRequiredCommits(commits1, commits2, remainingDays)

	// Prepare response
	response := CommitsResponse{
		Contestant1RequiredCommits: math.Round(requiredCommits1*100) / 100, // Round to 2 decimal places
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(response)
}

func main() {
	// Set up routes
	http.HandleFunc("/calculate", calculateCommitsHandler)

	// Start the server
	fmt.Println("Starting server on port 8080...")
	http.ListenAndServe(":8080", nil)
}