// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>

package forge

package oldgit

import (
	"bytes"
	"fmt"
	"strings"
	"time"

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

// fmtCommitPatch formats a commit object as if it was returned by

// FmtCommitPatch formats a commit object as if it was returned by

// git-format-patch.

func fmtCommitPatch(commit *object.Commit) (final string, err error) {

func FmtCommitPatch(commit *object.Commit) (final string, err error) {

	var patch *object.Patch
	var buf bytes.Buffer
	var author object.Signature
	var date string
	var commitTitle, commitDetails string

	if _, patch, err = commitToPatch(commit); err != nil {

	if _, patch, err = CommitToPatch(commit); err != nil {

		return "", err
	}

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

	commitTitle, commitDetails, _ = strings.Cut(commit.Message, "\n")

	// This date is hardcoded in Git.
	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", commitTitle)

	if commitDetails != "" {
		commitDetails1, commitDetails2, _ := strings.Cut(commitDetails, "\n")
		if strings.TrimSpace(commitDetails1) == "" {
			commitDetails = commitDetails2
		}
		buf.WriteString(commitDetails)
		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
}

// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>

package forge

import (
	"context"
	"errors"
	"io"
	"iter"

	"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/jackc/pgx/v5/pgtype"
)

// openRepo opens a git repository by group and repo name.
//
// TODO: This should be deprecated in favor of doing it in the relevant
// request/router context in the future, as it cannot cover the nuance of
// fields needed.
func (s *Server) openRepo(ctx context.Context, groupPath []string, repoName string) (repo *git.Repository, description string, repoID int, fsPath string, err error) {
	err = s.database.QueryRow(ctx, `
WITH RECURSIVE group_path_cte AS (
	-- Start: match the first name in the path where parent_group IS NULL
	SELECT
		id,
		parent_group,
		name,
		1 AS depth
	FROM groups
	WHERE name = ($1::text[])[1]
		AND parent_group IS NULL

	UNION ALL

	-- Recurse: join next segment of the path
	SELECT
		g.id,
		g.parent_group,
		g.name,
		group_path_cte.depth + 1
	FROM groups g
	JOIN group_path_cte ON g.parent_group = group_path_cte.id
	WHERE g.name = ($1::text[])[group_path_cte.depth + 1]
		AND group_path_cte.depth + 1 <= cardinality($1::text[])
)
SELECT
	r.filesystem_path,
	COALESCE(r.description, ''),
	r.id
FROM group_path_cte g
JOIN repos r ON r.group_id = g.id
WHERE g.depth = cardinality($1::text[])
	AND r.name = $2
	`, pgtype.FlatArray[string](groupPath), repoName).Scan(&fsPath, &description, &repoID)
	if err != nil {
		return
	}

	repo, err = git.PlainOpen(fsPath)
	return
}

// commitIterSeqErr creates an [iter.Seq[*object.Commit]] from an
// [object.CommitIter], and additionally returns a pointer to error.
// The pointer to error is guaranteed to be populated with either nil or the
// error returned by the commit iterator after the returned iterator is
// finished.
func commitIterSeqErr(commitIter object.CommitIter) (iter.Seq[*object.Commit], *error) {
	var err error
	return func(yield func(*object.Commit) bool) {
		for {
			commit, err2 := commitIter.Next()
			if err2 != nil {
				if errors.Is(err2, io.EOF) {
					return
				}
				err = err2
				return
			}
			if !yield(commit) {
				return
			}
		}
	}, &err
}

// commitToPatch creates an [object.Patch] from the first parent of a given
// [object.Commit].
//
// TODO: This function should be deprecated as it only diffs with the first
// parent and does not correctly handle merge commits.
func commitToPatch(commit *object.Commit) (parentCommitHash plumbing.Hash, patch *object.Patch, err error) {
	var parentCommit *object.Commit
	var commitTree *object.Tree

	parentCommit, err = commit.Parent(0)
	switch {
	case errors.Is(err, object.ErrParentNotFound):
		if commitTree, err = commit.Tree(); err != nil {
			return
		}
		if patch, err = nullTree.Patch(commitTree); err != nil {
			return
		}
	case err != nil:
		return
	default:
		parentCommitHash = parentCommit.Hash
		if patch, err = parentCommit.Patch(commit); err != nil {
			return
		}
	}
	return
}

var nullTree object.Tree //nolint:gochecknoglobals

// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>

package forge

import (
	"fmt"
	"net/http"
	"strings"

	"github.com/go-git/go-git/v5"
	"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/forge/internal/misc"

	"go.lindenii.runxiyu.org/forge/internal/oldgit"

	"go.lindenii.runxiyu.org/forge/internal/web"
)

// usableFilePatch is a [diff.FilePatch] that is structured in a way more
// friendly for use in HTML templates.
type usableFilePatch struct {
	From   diff.File
	To     diff.File
	Chunks []usableChunk
}

// usableChunk is a [diff.Chunk] that is structured in a way more friendly for
// use in HTML templates.
type usableChunk struct {
	Operation diff.Operation
	Content   string
}

func (s *Server) httpHandleRepoCommit(writer http.ResponseWriter, request *http.Request, params map[string]any) {
	var repo *git.Repository
	var commitIDStrSpec, commitIDStrSpecNoSuffix string
	var commitID plumbing.Hash
	var parentCommitHash plumbing.Hash
	var commitObj *object.Commit
	var commitIDStr string
	var err error
	var patch *object.Patch

	repo, commitIDStrSpec = params["repo"].(*git.Repository), params["commit_id"].(string)

	commitIDStrSpecNoSuffix = strings.TrimSuffix(commitIDStrSpec, ".patch")
	commitID = plumbing.NewHash(commitIDStrSpecNoSuffix)
	if commitObj, err = repo.CommitObject(commitID); err != nil {
		web.ErrorPage500(s.templates, writer, params, "Error getting commit object: "+err.Error())
		return
	}
	if commitIDStrSpecNoSuffix != commitIDStrSpec {
		var patchStr string

		if patchStr, err = fmtCommitPatch(commitObj); err != nil {

		if patchStr, err = oldgit.FmtCommitPatch(commitObj); err != nil {

			web.ErrorPage500(s.templates, writer, params, "Error formatting patch: "+err.Error())
			return
		}
		fmt.Fprintln(writer, patchStr)
		return
	}
	commitIDStr = commitObj.Hash.String()

	if commitIDStr != commitIDStrSpec {
		http.Redirect(writer, request, commitIDStr, http.StatusSeeOther)
		return
	}

	params["commit_object"] = commitObj
	params["commit_id"] = commitIDStr

	parentCommitHash, patch, err = commitToPatch(commitObj)

	parentCommitHash, patch, err = oldgit.CommitToPatch(commitObj)

	if err != nil {
		web.ErrorPage500(s.templates, writer, params, "Error getting patch from commit: "+err.Error())
		return
	}
	params["parent_commit_hash"] = parentCommitHash.String()
	params["patch"] = patch

	params["file_patches"] = makeUsableFilePatches(patch)

	s.renderTemplate(writer, "repo_commit", params)
}

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

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

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

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

var nullFakeDiffFile = fakeDiffFile{ //nolint:gochecknoglobals
	hash: plumbing.NewHash("0000000000000000000000000000000000000000"),
	mode: misc.FirstOrPanic(filemode.New("100644")),
	path: "",
}

func makeUsableFilePatches(patch diff.Patch) (usableFilePatches []usableFilePatch) {
	// TODO: Remove unnecessary context
	// TODO: Prepend "+"/"-"/" " instead of solely distinguishing based on color

	for _, filePatch := range patch.FilePatches() {
		var fromFile, toFile diff.File
		var ufp usableFilePatch
		chunks := []usableChunk{}

		fromFile, toFile = filePatch.Files()
		if fromFile == nil {
			fromFile = nullFakeDiffFile
		}
		if toFile == nil {
			toFile = nullFakeDiffFile
		}
		for _, chunk := range filePatch.Chunks() {
			var content string

			content = chunk.Content()
			if len(content) > 0 && content[0] == '\n' {
				content = "\n" + content
			} // Horrible hack to fix how browsers newlines that immediately proceed <pre>
			chunks = append(chunks, usableChunk{
				Operation: chunk.Type(),
				Content:   content,
			})
		}
		ufp = usableFilePatch{
			Chunks: chunks,
			From:   fromFile,
			To:     toFile,
		}
		usableFilePatches = append(usableFilePatches, ufp)
	}
	return
}

package oldgit

import (
	"errors"

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

// CommitToPatch creates an [object.Patch] from the first parent of a given
// [object.Commit].
//
// TODO: This function should be deprecated as it only diffs with the first
// parent and does not correctly handle merge commits.
func CommitToPatch(commit *object.Commit) (parentCommitHash plumbing.Hash, patch *object.Patch, err error) {
	var parentCommit *object.Commit
	var commitTree *object.Tree

	parentCommit, err = commit.Parent(0)
	switch {
	case errors.Is(err, object.ErrParentNotFound):
		if commitTree, err = commit.Tree(); err != nil {
			return
		}
		if patch, err = NullTree.Patch(commitTree); err != nil {
			return
		}
	case err != nil:
		return
	default:
		parentCommitHash = parentCommit.Hash
		if patch, err = parentCommit.Patch(commit); err != nil {
			return
		}
	}
	return
}

var NullTree object.Tree //nolint:gochecknoglobals