// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileContributor: Runxi Yu <https://runxiyu.org>

package main

import (
	"html/template"
	"iter"
	"net/http"
	"strings"
	"time"

	"github.com/dgraph-io/ristretto/v2"
	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"github.com/go-git/go-git/v5/plumbing/object"
	"github.com/go-git/go-git/v5/plumbing/storer"
	"go.lindenii.runxiyu.org/lindenii-common/clog"
)

type indexPageCacheEntry struct {
	DisplayTree    []displayTreeEntry
	ReadmeFilename string
	ReadmeRendered template.HTML
}

var indexPageCache *ristretto.Cache[[]byte, indexPageCacheEntry]

func init() {
	var err error
	indexPageCache, err = ristretto.NewCache(&ristretto.Config[[]byte, indexPageCacheEntry]{
		NumCounters: 1e4,
		MaxCost:     1 << 30,
		BufferItems: 64,
	})
	if err != nil {
		clog.Fatal(1, "Error initializing indexPageCache: "+err.Error())
	}
}

func httpHandleRepoIndex(writer http.ResponseWriter, _ *http.Request, params map[string]any) {
	var repo *git.Repository
	var repoName string
	var groupPath []string
	var refHash plumbing.Hash
	var refHashSlice []byte
	var err error
	var logOptions git.LogOptions
	var commitIter object.CommitIter
	var commitIterSeq iter.Seq[*object.Commit]
	var commitObj *object.Commit
	var tree *object.Tree
	var notes []string
	var branches []string
	var branchesIter storer.ReferenceIter

	repo, repoName, groupPath = params["repo"].(*git.Repository), params["repo_name"].(string), params["group_path"].([]string)

	if strings.Contains(repoName, "\n") || sliceContainsNewlines(groupPath) {
		notes = append(notes, "Path contains newlines; HTTP Git access impossible")
	}

	refHash, err = getRefHash(repo, params["ref_type"].(string), params["ref_name"].(string))
	if err != nil {
		goto no_ref
	}
	refHashSlice = refHash[:]

	branchesIter, err = repo.Branches()
	if err == nil {
		_ = branchesIter.ForEach(func(branch *plumbing.Reference) error {
			branches = append(branches, branch.Name().Short())
			return nil
		})
	}
	params["branches"] = branches

	// TODO: Cache
	logOptions = git.LogOptions{From: refHash} //exhaustruct:ignore
	if commitIter, err = repo.Log(&logOptions); err != nil {
		goto no_ref
	}
	commitIterSeq, params["commits_err"] = commitIterSeqErr(commitIter)
	params["commits"] = iterSeqLimit(commitIterSeq, 3)

	if value, found := indexPageCache.Get(refHashSlice); found {
		params["files"] = value.DisplayTree
		params["readme_filename"] = value.ReadmeFilename
		params["readme"] = value.ReadmeRendered
	} else {
		start := time.Now()
		if commitObj, err = repo.CommitObject(refHash); err != nil {
			goto no_ref
		}

		if tree, err = commitObj.Tree(); err != nil {
			goto no_ref
		}
		displayTree := makeDisplayTree(tree)
		readmeFilename, readmeRendered := renderReadmeAtTree(tree)
		cost := time.Since(start).Nanoseconds()

		params["files"] = displayTree
		params["readme_filename"] = readmeFilename
		params["readme"] = readmeRendered

		entry := indexPageCacheEntry{
			DisplayTree:    displayTree,
			ReadmeFilename: readmeFilename,
			ReadmeRendered: readmeRendered,
		}
		indexPageCache.Set(refHashSlice, entry, cost)
	}

no_ref:

	params["http_clone_url"] = genHTTPRemoteURL(groupPath, repoName)
	params["ssh_clone_url"] = genSSHRemoteURL(groupPath, repoName)
	params["notes"] = notes

	renderTemplate(writer, "repo_index", params)
}