package server

import (
	"errors"
	"fmt"
	"net/http"
	"regexp"

	"g.fc.run/misc/byre/internal/api"
	"g.fc.run/misc/byre/internal/git"
)

var objectID = regexp.MustCompile(`^[0-9a-f]{40}([0-9a-f]{24})?$`)

func (s *Server) GetTaskChanges(w http.ResponseWriter, r *http.Request, taskID string, params api.GetTaskChangesParams) {
	t, err := s.store.GetTask(r.Context(), taskID)
	if err != nil {
		writeStoreError(w, err)
		return
	}
	if t.Status != api.TaskStatusActive {
		writeError(w, http.StatusConflict, fmt.Errorf("task %s is %s and has no worktree", t.Id, t.Status))
		return
	}

	p, err := s.store.GetProject(r.Context(), t.ProjectId)
	if err != nil {
		writeStoreError(w, err)
		return
	}

	since := ""
	if params.Since != nil {
		since = *params.Since
		if !objectID.MatchString(since) {
			writeError(w, http.StatusBadRequest, errors.New("since must be a full object id"))
			return
		}
	}

	changes, err := git.Changes(t.WorktreePath, p.DefaultBranch, since)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}
	writeJSON(w, http.StatusOK, changes)
}

func (s *Server) GetTaskDiff(w http.ResponseWriter, r *http.Request, taskID string, params api.GetTaskDiffParams) {
	t, err := s.store.GetTask(r.Context(), taskID)
	if err != nil {
		writeStoreError(w, err)
		return
	}
	if t.Status != api.TaskStatusActive {
		writeError(w, http.StatusConflict, fmt.Errorf("task %s is %s and has no worktree", t.Id, t.Status))
		return
	}
	if !objectID.MatchString(params.Base) || !objectID.MatchString(params.Tree) {
		writeError(w, http.StatusBadRequest, errors.New("base and tree must be full object ids"))
		return
	}

	oldPath := ""
	if params.OldPath != nil {
		oldPath = *params.OldPath
	}
	patch, err := git.FileDiff(t.WorktreePath, params.Base, params.Tree, params.Path, oldPath)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}
	writeJSON(w, http.StatusOK, api.FileDiff{Path: params.Path, Patch: patch})
}