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

package main

import (
	"bytes"
	"html/template"
	"net/http"
	"path"
	"strings"

	"github.com/alecthomas/chroma/v2"
	chroma_formatters_html "github.com/alecthomas/chroma/v2/formatters/html"
	chroma_lexers "github.com/alecthomas/chroma/v2/lexers"
	chroma_styles "github.com/alecthomas/chroma/v2/styles"
	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"github.com/go-git/go-git/v5/plumbing/object"
)

func handle_repo_tree(w http.ResponseWriter, r *http.Request, params map[string]any) {
	var raw_path_spec, path_spec string
	var repo *git.Repository
	var ref_hash plumbing.Hash
	var commit_object *object.Commit
	var tree *object.Tree
	var err error

	raw_path_spec = params["rest"].(string)
	repo, path_spec = params["repo"].(*git.Repository), strings.TrimSuffix(raw_path_spec, "/")
	params["path_spec"] = path_spec

	if ref_hash, err = get_ref_hash_from_type_and_name(repo, params["ref_type"].(string), params["ref_name"].(string)); err != nil {
		http.Error(w, "Error getting ref hash: "+err.Error(), http.StatusInternalServerError)
		return
	}
	if commit_object, err = repo.CommitObject(ref_hash); err != nil {
		http.Error(w, "Error getting commit object: "+err.Error(), http.StatusInternalServerError)
		return
	}
	if tree, err = commit_object.Tree(); err != nil {
		http.Error(w, "Error getting file tree: "+err.Error(), http.StatusInternalServerError)
		return
	}

	var target *object.Tree
	if path_spec == "" {
		target = tree
	} else {
		if target, err = tree.Tree(path_spec); err != nil {
			var file *object.File
			var file_contents string
			var lexer chroma.Lexer
			var iterator chroma.Iterator
			var style *chroma.Style
			var formatter *chroma_formatters_html.Formatter
			var formatted_encapsulated template.HTML

			if file, err = tree.File(path_spec); err != nil {
				http.Error(w, "Error retrieving path: "+err.Error(), http.StatusInternalServerError)
				return
			}
			if len(raw_path_spec) != 0 && raw_path_spec[len(raw_path_spec)-1] == '/' {
				http.Redirect(w, r, "../"+path_spec, http.StatusSeeOther)
				return
			}
			if file_contents, err = file.Contents(); err != nil {
				http.Error(w, "Error reading file: "+err.Error(), http.StatusInternalServerError)
				return
			}
			lexer = chroma_lexers.Match(path_spec)
			if lexer == nil {
				lexer = chroma_lexers.Fallback
			}
			if iterator, err = lexer.Tokenise(nil, file_contents); err != nil {
				http.Error(w, "Error tokenizing code: "+err.Error(), http.StatusInternalServerError)
				return
			}
			var formatted_unencapsulated bytes.Buffer
			style = chroma_styles.Get("autumn")
			formatter = chroma_formatters_html.New(chroma_formatters_html.WithClasses(true), chroma_formatters_html.TabWidth(8))
			if err = formatter.Format(&formatted_unencapsulated, style, iterator); err != nil {
				http.Error(w, "Error formatting code: "+err.Error(), http.StatusInternalServerError)
				return
			}
			formatted_encapsulated = template.HTML(formatted_unencapsulated.Bytes()) //#nosec G203
			params["file_contents"] = formatted_encapsulated

			render_template(w, "repo_tree_file", params)
			return
		}
	}

	if len(raw_path_spec) != 0 && raw_path_spec[len(raw_path_spec)-1] != '/' {
		http.Redirect(w, r, path.Base(path_spec)+"/", http.StatusSeeOther)
		return
	}

	params["readme_filename"], params["readme"] = render_readme_at_tree(target)
	params["files"] = build_display_git_tree(target)

	render_template(w, "repo_tree_dir", params)
}