// SPDX-License-Identifier: EUPL-1.2

package agentic

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"

	coreerr "forge.lthn.ai/core/go-log"
	"github.com/modelcontextprotocol/go-sdk/mcp"
)

// ScanInput is the input for agentic_scan.
type ScanInput struct {
	Org    string   `json:"org,omitempty"`    // default "core"
	Labels []string `json:"labels,omitempty"` // filter by labels (default: agentic, help-wanted, bug)
	Limit  int      `json:"limit,omitempty"`  // max issues to return
}

// ScanOutput is the output for agentic_scan.
type ScanOutput struct {
	Success bool        `json:"success"`
	Count   int         `json:"count"`
	Issues  []ScanIssue `json:"issues"`
}

// ScanIssue is a single actionable issue.
type ScanIssue struct {
	Repo     string   `json:"repo"`
	Number   int      `json:"number"`
	Title    string   `json:"title"`
	Labels   []string `json:"labels"`
	Assignee string   `json:"assignee,omitempty"`
	URL      string   `json:"url"`
}

func (s *PrepSubsystem) scan(ctx context.Context, _ *mcp.CallToolRequest, input ScanInput) (*mcp.CallToolResult, ScanOutput, error) {
	if s.forgeToken == "" {
		return nil, ScanOutput{}, coreerr.E("scan", "no Forge token configured", nil)
	}

	if input.Org == "" {
		input.Org = "core"
	}
	if input.Limit == 0 {
		input.Limit = 20
	}
	if len(input.Labels) == 0 {
		input.Labels = []string{"agentic", "help-wanted", "bug"}
	}

	var allIssues []ScanIssue

	// Get repos for the org
	repos, err := s.listOrgRepos(ctx, input.Org)
	if err != nil {
		return nil, ScanOutput{}, err
	}

	for _, repo := range repos {
		for _, label := range input.Labels {
			issues, err := s.listRepoIssues(ctx, input.Org, repo, label)
			if err != nil {
				continue
			}
			allIssues = append(allIssues, issues...)

			if len(allIssues) >= input.Limit {
				break
			}
		}
		if len(allIssues) >= input.Limit {
			break
		}
	}

	// Deduplicate by repo+number
	seen := make(map[string]bool)
	var unique []ScanIssue
	for _, issue := range allIssues {
		key := fmt.Sprintf("%s#%d", issue.Repo, issue.Number)
		if !seen[key] {
			seen[key] = true
			unique = append(unique, issue)
		}
	}

	if len(unique) > input.Limit {
		unique = unique[:input.Limit]
	}

	return nil, ScanOutput{
		Success: true,
		Count:   len(unique),
		Issues:  unique,
	}, nil
}

func (s *PrepSubsystem) listOrgRepos(ctx context.Context, org string) ([]string, error) {
	url := fmt.Sprintf("%s/api/v1/orgs/%s/repos?limit=50", s.forgeURL, org)
	req, _ := http.NewRequestWithContext(ctx, "GET", url, nil)
	req.Header.Set("Authorization", "token "+s.forgeToken)

	resp, err := s.client.Do(req)
	if err != nil {
		return nil, coreerr.E("scan.listOrgRepos", "failed to list repos", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, coreerr.E("scan.listOrgRepos", "failed to list repos", err)
	}
	defer resp.Body.Close()

	var repos []struct {
		Name string `json:"name"`
	}
	json.NewDecoder(resp.Body).Decode(&repos)

	var names []string
	for _, r := range repos {
		names = append(names, r.Name)
	}
	return names, nil
}

func (s *PrepSubsystem) listRepoIssues(ctx context.Context, org, repo, label string) ([]ScanIssue, error) {
	url := fmt.Sprintf("%s/api/v1/repos/%s/%s/issues?state=open&labels=%s&limit=10&type=issues",
		s.forgeURL, org, repo, label)
	req, _ := http.NewRequestWithContext(ctx, "GET", url, nil)
	req.Header.Set("Authorization", "token "+s.forgeToken)

	resp, err := s.client.Do(req)
	if err != nil {
		return nil, coreerr.E("scan.listRepoIssues", "failed to list issues for "+repo, err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, coreerr.E("scan.listRepoIssues", "failed to list issues for "+repo, err)
	}
	defer resp.Body.Close()

	var issues []struct {
		Number int    `json:"number"`
		Title  string `json:"title"`
		Labels []struct {
			Name string `json:"name"`
		} `json:"labels"`
		Assignee *struct {
			Login string `json:"login"`
		} `json:"assignee"`
		HTMLURL string `json:"html_url"`
	}
	json.NewDecoder(resp.Body).Decode(&issues)

	var result []ScanIssue
	for _, issue := range issues {
		var labels []string
		for _, l := range issue.Labels {
			labels = append(labels, l.Name)
		}
		assignee := ""
		if issue.Assignee != nil {
			assignee = issue.Assignee.Login
		}

		result = append(result, ScanIssue{
			Repo:     repo,
			Number:   issue.Number,
			Title:    issue.Title,
			Labels:   labels,
			Assignee: assignee,
			URL:      strings.Replace(issue.HTMLURL, "https://forge.lthn.ai", s.forgeURL, 1),
		})
	}

	return result, nil
}