package reports

import (
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"time"

	"gopkg.in/yaml.v3"

	"github.com/atridad/wrapped-cli/pkg/config"
	"github.com/atridad/wrapped-cli/pkg/models"
)

type ReportMetadata struct {
	Timestamp    time.Time            `yaml:"timestamp"`
	Username     string               `yaml:"username"`
	TotalCommits int                  `yaml:"total_commits"`
	Repositories int                  `yaml:"repositories"`
	Stats        *models.UserStats    `yaml:"stats"`
}

type Report struct {
	Metadata   *ReportMetadata
	MarkdownID string
	MetadataID string
	Timestamp  time.Time
}

func SaveReport(stats *models.UserStats) (string, error) {
	resultsDir, err := config.GetResultsDir()
	if err != nil {
		return "", err
	}

	now := time.Now()
	timestamp := now.Format("2006-01-02 15-04-05")
	metadataID := fmt.Sprintf("%s.yaml", now.Format("2006-01-02-15-04-05"))
	imageID := fmt.Sprintf("%s - Gitea Wrapped.png", timestamp)

	metadata := &ReportMetadata{
		Timestamp:    now,
		Username:     stats.Username,
		TotalCommits: stats.TotalCommits,
		Repositories: stats.TotalRepositories,
		Stats:        stats,
	}

	metadataPath := filepath.Join(resultsDir, metadataID)
	data, err := yaml.Marshal(metadata)
	if err != nil {
		return "", err
	}

	if err := os.WriteFile(metadataPath, data, 0o644); err != nil {
		return "", err
	}

	if _, err := ExportReportAsImage(stats, "png"); err != nil {
		fmt.Fprintf(os.Stderr, "Warning: failed to generate image: %v\n", err)
	}

	return imageID, nil
}

func ListReports() ([]Report, error) {
	resultsDir, err := config.GetResultsDir()
	if err != nil {
		return nil, err
	}

	entries, err := os.ReadDir(resultsDir)
	if err != nil {
		if os.IsNotExist(err) {
			return []Report{}, nil
		}
		return nil, err
	}

	var reports []Report
	for _, entry := range entries {
		if entry.IsDir() {
			continue
		}

		if filepath.Ext(entry.Name()) == ".yaml" {
			metadataPath := filepath.Join(resultsDir, entry.Name())
			data, err := os.ReadFile(metadataPath)
			if err != nil {
				continue
			}

			var metadata ReportMetadata
			if err := yaml.Unmarshal(data, &metadata); err != nil {
				continue
			}

			reports = append(reports, Report{
				Metadata:   &metadata,
				MetadataID: entry.Name(),
				Timestamp:  metadata.Timestamp,
			})
		}
	}

	sort.Slice(reports, func(i, j int) bool {
		return reports[i].Timestamp.After(reports[j].Timestamp)
	})

	return reports, nil
}

func GetReport(metadataID string) (*ReportMetadata, error) {
	resultsDir, err := config.GetResultsDir()
	if err != nil {
		return nil, err
	}

	metadataPath := filepath.Join(resultsDir, metadataID)
	data, err := os.ReadFile(metadataPath)
	if err != nil {
		return nil, err
	}

	var metadata ReportMetadata
	if err := yaml.Unmarshal(data, &metadata); err != nil {
		return nil, err
	}

	return &metadata, nil
}

func generateMarkdown(stats *models.UserStats) string {
	md := fmt.Sprintf("# Gitea Wrapped — %s\n\n", time.Now().Format("January 2, 2006"))

	md += fmt.Sprintf("**User**: %s\n\n", stats.Username)

	md += "## Overview\n\n"
	md += fmt.Sprintf("- **Total Commits**: %d\n", stats.TotalCommits)
	md += fmt.Sprintf("- **Total Repositories**: %d\n", stats.TotalRepositories)
	md += fmt.Sprintf("- **Average Commits/Day**: %.2f\n", stats.AverageCommitsPerDay)
	md += fmt.Sprintf("- **Most Active Day**: %s\n", stats.MostActiveDay)
	md += fmt.Sprintf("- **Most Active Month**: %s\n\n", stats.MostActiveMonth)

	md += "## Languages\n\n"
	for i, lang := range stats.Languages {
		if i >= 10 {
			break
		}
		md += fmt.Sprintf("- %s: %d repos (%.1f%%)\n", lang.Language, lang.Count, lang.Percent)
	}
	md += "\n"

	md += "## Top Repositories\n\n"
	for i, repo := range stats.TopRepositories {
		md += fmt.Sprintf("%d. [%s](%s)\n", i+1, repo.Name, repo.HTMLURL)
	}
	md += "\n"

	md += "## Most Active Days\n\n"
	for i, day := range stats.CommitsByWeekday {
		if i >= 7 {
			break
		}
		md += fmt.Sprintf("- %s: %d commits\n", day.Day, day.Count)
	}
	md += "\n"

	md += "## Most Active Months\n\n"
	for i, month := range stats.CommitsByMonth {
		if i >= 12 {
			break
		}
		md += fmt.Sprintf("- %s: %d commits\n", month.Date.Format("January 2006"), month.Count)
	}

	return md
}