package modules

import (
	"strconv"

	"gsg/internal/core"
	"gsg/internal/gitx"
)

func init() { core.Register("log", logMod) }

// LogPage is one page of commit history, with enough to render prev/next
// links without a separate count query (see the n+1 fetch trick below).
type LogPage struct {
	Commits          []gitx.Commit
	Ofs, PageSize    int
	HasPrev, HasNext bool
	PrevOfs, NextOfs int
}

// log: a page of recent commits.  {{ mod "log" "20" }}  -- default
// core.LogPageSize, "0" = all. Paginated via the ?ofs= query param on the
// log route (see buildCtx), which core.LogPageSize must match.
func logMod(c *core.Ctx, args ...string) (any, error) {
	n := core.LogPageSize
	if len(args) > 0 {
		if v, err := strconv.Atoi(args[0]); err == nil {
			n = v
		}
	}
	ofs, _ := strconv.Atoi(c.Var("ofs"))
	if ofs < 0 {
		ofs = 0
	}
	rev := c.Commit
	if rev == "" {
		rev = c.Ref
	}

	fetch := n
	if n > 0 {
		fetch = n + 1 // one extra row to detect a next page
	}
	commits, err := c.Repo.Log(rev, fetch, ofs, true)
	if err != nil {
		return nil, err
	}

	page := LogPage{Ofs: ofs, PageSize: n, HasPrev: ofs > 0, PrevOfs: ofs - n}
	if page.PrevOfs < 0 {
		page.PrevOfs = 0
	}
	if n > 0 && len(commits) > n {
		commits = commits[:n]
		page.HasNext, page.NextOfs = true, ofs+n
	}
	page.Commits = commits
	return page, nil
}