package main

import (
	"bytes"

	"errors"

	"fmt"
	"strings"
	"time"

	"github.com/go-git/go-git/v5/plumbing/object"
	"go.lindenii.runxiyu.org/lindenii-common/misc"
)

var err_get_patch = errors.New("Failed to get patch from commit")

func format_patch_from_commit(commit *object.Commit) (string, error) {

	parent, err := commit.Parent(0)

	_, patch, err := get_patch_from_commit(commit)

	if err != nil {

		return "", err
	}

	var patch *object.Patch
	patch, err = parent.Patch(commit)
	if err != nil {
		return "", misc.Wrap_one_error(err_get_patch, err)

		return "", misc.Wrap_one_error(err_getting_patch_of_commit, err)

	}

	var buf bytes.Buffer

	author := commit.Author
	date := author.When.Format(time.RFC1123Z)

	commit_msg_title, commit_msg_details, _ := strings.Cut(commit.Message, "\n")

	fmt.Fprintf(&buf, "From %s Mon Sep 17 00:00:00 2001\n", commit.Hash)
	fmt.Fprintf(&buf, "From: %s <%s>\n", author.Name, author.Email)
	fmt.Fprintf(&buf, "Date: %s\n", date)
	fmt.Fprintf(&buf, "Subject: [PATCH] %s\n\n", commit_msg_title)

	if commit_msg_details != "" {
		fmt.Println("fdsafsad")
		commit_msg_details_first_line, commit_msg_details_rest, _ := strings.Cut(commit_msg_details, "\n")
		if strings.TrimSpace(commit_msg_details_first_line) == "" {
			commit_msg_details = commit_msg_details_rest
		}
		buf.WriteString(commit_msg_details)
		buf.WriteString("\n")
	}
	buf.WriteString("---\n")
	fmt.Fprint(&buf, patch.Stats().String())
	fmt.Fprintln(&buf)

	buf.WriteString(patch.String())

	fmt.Fprintf(&buf, "\n-- \n2.48.1\n")

	return buf.String(), nil
}

package main

import (
	"errors"
	"io"
	"path/filepath"
	"strings"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"github.com/go-git/go-git/v5/plumbing/object"
	"go.lindenii.runxiyu.org/lindenii-common/misc"
)

var err_unsafe_path = errors.New("Unsafe path")

var err_getting_commit_tree = errors.New("Error getting commit tree")
var err_getting_patch_of_commit = errors.New("Error getting patch of commit")
var err_getting_parent_commit_object = errors.New("Error getting parent commit object")

func open_git_repo(group_name, repo_name string) (*git.Repository, error) {
	group_name, group_name_ok := misc.Sanitize_path(group_name)
	if !group_name_ok {
		return nil, err_unsafe_path
	}
	repo_name, repo_name_ok := misc.Sanitize_path(repo_name)
	if !repo_name_ok {
		return nil, err_unsafe_path
	}
	return git.PlainOpen(filepath.Join(config.Git.Root, group_name, repo_name+".git"))
}

func build_display_git_tree(tree *object.Tree) []display_git_tree_entry_t {
	display_git_tree := make([]display_git_tree_entry_t, 0)
	for _, entry := range tree.Entries {
		display_git_tree_entry := display_git_tree_entry_t{}
		os_mode, err := entry.Mode.ToOSFileMode()
		if err != nil {
			display_git_tree_entry.Mode = "x---"
		} else {
			display_git_tree_entry.Mode = os_mode.String()[:4]
		}
		display_git_tree_entry.Is_file = entry.Mode.IsFile()
		display_git_tree_entry.Size, err = tree.Size(entry.Name)
		if err != nil {
			display_git_tree_entry.Size = 0
		}
		display_git_tree_entry.Name = strings.TrimPrefix(entry.Name, "/")
		display_git_tree = append(display_git_tree, display_git_tree_entry)
	}
	return display_git_tree
}

var err_get_recent_commits = errors.New("Error getting recent commits:")

func get_recent_commits(repo *git.Repository, head_hash plumbing.Hash, number_of_commits int) (recent_commits []*object.Commit, err error) {
	commit_iter, err := repo.Log(&git.LogOptions{From: head_hash})
	if err != nil {
		err = misc.Wrap_one_error(err_get_recent_commits, err)
		return nil, err
	}
	recent_commits = make([]*object.Commit, 0)
	defer commit_iter.Close()
	if number_of_commits < 0 {
		for {
			this_recent_commit, err := commit_iter.Next()
			if errors.Is(err, io.EOF) {
				return recent_commits, nil
			} else if err != nil {
				err = misc.Wrap_one_error(err_get_recent_commits, err)
				return nil, err
			}
			recent_commits = append(recent_commits, this_recent_commit)
		}
	} else {
		for range number_of_commits {
			this_recent_commit, err := commit_iter.Next()
			if errors.Is(err, io.EOF) {
				return recent_commits, nil
			} else if err != nil {
				err = misc.Wrap_one_error(err_get_recent_commits, err)
				return nil, err
			}
			recent_commits = append(recent_commits, this_recent_commit)
		}
	}
	return recent_commits, err
}

func get_patch_from_commit(commit_object *object.Commit) (parent_commit_hash plumbing.Hash, patch *object.Patch, ret_err error) {
	parent_commit_object, err := commit_object.Parent(0)
	if errors.Is(err, object.ErrParentNotFound) {
		commit_tree, err := commit_object.Tree()
		if err != nil {
			ret_err = misc.Wrap_one_error(err_getting_commit_tree, err)
			return
		}
		patch, err = (&object.Tree{}).Patch(commit_tree)
		if err != nil {
			ret_err = misc.Wrap_one_error(err_getting_patch_of_commit, err)
			return
		}
	} else if err != nil {
		ret_err = misc.Wrap_one_error(err_getting_parent_commit_object, err)
		return
	} else {
		parent_commit_hash = parent_commit_object.Hash
		patch, err = parent_commit_object.Patch(commit_object)
		if err != nil {
			ret_err = misc.Wrap_one_error(err_getting_patch_of_commit, err)
			return
		}
	}
	return
}

package main

import (

	"errors"

	"net/http"
	"strings"

	"github.com/go-git/go-git/v5/plumbing"
	"github.com/go-git/go-git/v5/plumbing/filemode"
	"github.com/go-git/go-git/v5/plumbing/format/diff"

	"github.com/go-git/go-git/v5/plumbing/object"

	"go.lindenii.runxiyu.org/lindenii-common/misc"
)

type usable_file_patch struct {
	From   diff.File
	To     diff.File
	Chunks []diff.Chunk
}

func handle_repo_commit(w http.ResponseWriter, r *http.Request) {
	data := make(map[string]any)
	group_name, repo_name, commit_id_specified_string := r.PathValue("group_name"), r.PathValue("repo_name"), r.PathValue("commit_id")
	data["group_name"], data["repo_name"] = group_name, repo_name
	repo, err := open_git_repo(group_name, repo_name)
	if err != nil {
		_, _ = w.Write([]byte("Error opening repo: " + err.Error()))
		return
	}
	commit_id_specified_string_without_suffix := strings.TrimSuffix(commit_id_specified_string, ".patch")
	commit_id := plumbing.NewHash(commit_id_specified_string_without_suffix)
	commit_object, err := repo.CommitObject(commit_id)
	if err != nil {
		_, _ = w.Write([]byte("Error getting commit object: " + err.Error()))
		return
	}
	if commit_id_specified_string_without_suffix != commit_id_specified_string {
		patch, err := format_patch_from_commit(commit_object)
		if err != nil {
			_, _ = w.Write([]byte("Error formatting patch: " + err.Error()))
			return
		}
		_, _ = w.Write([]byte(patch))
		return
	}
	commit_id_string := commit_object.Hash.String()

	if commit_id_string != commit_id_specified_string {
		http.Redirect(w, r, commit_id_string, http.StatusSeeOther)
		return
	}

	data["commit_object"] = commit_object
	data["commit_id"] = commit_id_string

	var patch *object.Patch
	parent_commit_object, err := commit_object.Parent(0)
	if errors.Is(err, object.ErrParentNotFound) {
		commit_tree, err := commit_object.Tree()
		if err != nil {
			_, _ = w.Write([]byte("Error getting commit tree (for comparing against an empty tree): " + err.Error()))
			return
		}
		patch, err = (&object.Tree{}).Patch(commit_tree)
		if err != nil {
			_, _ = w.Write([]byte("Error getting patch of commit: " + err.Error()))
			return
		}
	} else if err != nil {
		_, _ = w.Write([]byte("Error getting parent commit object: " + err.Error()))
		return
	} else {
		data["parent_commit_hash"] = parent_commit_object.Hash.String()

		patch, err = parent_commit_object.Patch(commit_object)
		if err != nil {
			_, _ = w.Write([]byte("Error getting patch of commit: " + err.Error()))
			return
		}
	}

	parent_commit_hash, patch, err := get_patch_from_commit(commit_object)
	data["parent_commit_hash"] = parent_commit_hash.String()

	data["patch"] = patch

	// TODO: Remove unnecessary context
	// TODO: Prepend "+"/"-"/" " instead of solely distinguishing based on color
	usable_file_patches := make([]usable_file_patch, 0)
	for _, file_patch := range patch.FilePatches() {
		from, to := file_patch.Files()
		if from == nil {
			from = fake_diff_file_null
		}
		if to == nil {
			to = fake_diff_file_null
		}
		usable_file_patch := usable_file_patch{
			Chunks: file_patch.Chunks(),
			From:   from,
			To:     to,
		}
		usable_file_patches = append(usable_file_patches, usable_file_patch)
	}
	data["file_patches"] = usable_file_patches

	err = templates.ExecuteTemplate(w, "repo_commit", data)
	if err != nil {
		_, _ = w.Write([]byte("Error rendering template: " + err.Error()))
		return
	}
}

type fake_diff_file struct {
	hash plumbing.Hash
	mode filemode.FileMode
	path string
}

func (f fake_diff_file) Hash() plumbing.Hash {
	return f.hash
}

func (f fake_diff_file) Mode() filemode.FileMode {
	return f.mode
}

func (f fake_diff_file) Path() string {
	return f.path
}

var fake_diff_file_null = fake_diff_file{
	hash: plumbing.NewHash("e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"),
	mode: misc.First_or_panic(filemode.New("100644")),
	path: "",
}