package handlers

import (
	"context"
	"errors"
	"log/slog"
	"strconv"

	"github.com/gin-gonic/gin"

	"git.netcell-it.de/projekte/edgeguard-native/internal/handlers/response"
	"git.netcell-it.de/projekte/edgeguard-native/internal/models"
	"git.netcell-it.de/projekte/edgeguard-native/internal/services/audit"
	"git.netcell-it.de/projekte/edgeguard-native/internal/services/domainheaders"
	"git.netcell-it.de/projekte/edgeguard-native/internal/services/domains"
	"git.netcell-it.de/projekte/edgeguard-native/internal/services/routingrules"
)

type DomainsHandler struct {
	Repo    *domains.Repo
	Routing *routingrules.Repo
	Headers *domainheaders.Repo
	Audit   *audit.Repo
	NodeID  string

	// Reloader regenerates and applies the haproxy config. Symmetric
	// to FirewallHandler.Reloader; called after every mutation so the
	// running haproxy.cfg always matches the DB. Errors are logged
	// but don't fail the API call (the row is committed and the
	// operator can re-trigger via `edgeguard-ctl render-config`).
	Reloader func(ctx context.Context) error
}

func NewDomainsHandler(repo *domains.Repo, routing *routingrules.Repo, headers *domainheaders.Repo, a *audit.Repo, nodeID string, reloader func(context.Context) error) *DomainsHandler {
	return &DomainsHandler{Repo: repo, Routing: routing, Headers: headers, Audit: a, NodeID: nodeID, Reloader: reloader}
}

func (h *DomainsHandler) reload(ctx context.Context, op string) {
	if h.Reloader == nil {
		return
	}
	if err := h.Reloader(ctx); err != nil {
		slog.Warn("haproxy: reload after domain mutation failed", "op", op, "error", err)
	}
}

func (h *DomainsHandler) Register(rg *gin.RouterGroup) {
	g := rg.Group("/domains")
	g.GET("", h.List)
	g.POST("", h.Create)
	g.GET("/:id", h.Get)
	g.PUT("/:id", h.Update)
	g.DELETE("/:id", h.Delete)
	g.GET("/:id/routing-rules", h.ListRoutingRules)

	g.GET("/:id/headers", h.ListHeaders)
	g.POST("/:id/headers", h.CreateHeader)
	g.PUT("/:id/headers/:hid", h.UpdateHeader)
	g.DELETE("/:id/headers/:hid", h.DeleteHeader)
}

func (h *DomainsHandler) List(c *gin.Context) {
	out, err := h.Repo.List(c.Request.Context())
	if err != nil {
		response.Internal(c, err)
		return
	}
	response.OK(c, gin.H{"domains": out})
}

func (h *DomainsHandler) Get(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}
	d, err := h.Repo.Get(c.Request.Context(), id)
	if err != nil {
		if errors.Is(err, domains.ErrNotFound) {
			response.NotFound(c, err)
			return
		}
		response.Internal(c, err)
		return
	}
	response.OK(c, d)
}

func (h *DomainsHandler) Create(c *gin.Context) {
	var req models.Domain
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err)
		return
	}
	out, err := h.Repo.Create(c.Request.Context(), req)
	if err != nil {
		response.Internal(c, err)
		return
	}
	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "domain.create", req.Name, out, h.NodeID)
	response.Created(c, out); h.reload(c.Request.Context(), "create")
}

func (h *DomainsHandler) Update(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}
	var req models.Domain
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err)
		return
	}
	out, err := h.Repo.Update(c.Request.Context(), id, req)
	if err != nil {
		if errors.Is(err, domains.ErrNotFound) {
			response.NotFound(c, err)
			return
		}
		response.Internal(c, err)
		return
	}
	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "domain.update", out.Name, out, h.NodeID)
	response.OK(c, out); h.reload(c.Request.Context(), "update")
}

func (h *DomainsHandler) Delete(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}
	if err := h.Repo.Delete(c.Request.Context(), id); err != nil {
		if errors.Is(err, domains.ErrNotFound) {
			response.NotFound(c, err)
			return
		}
		response.Internal(c, err)
		return
	}
	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "domain.delete",
		strconv.FormatInt(id, 10), gin.H{"id": id}, h.NodeID)
	response.NoContent(c); h.reload(c.Request.Context(), "delete")
}

// ListRoutingRules narrows /routing-rules to one domain — UI uses this
// for the per-domain rules tab rather than fetching the global list
// and filtering client-side.
func (h *DomainsHandler) ListRoutingRules(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}
	out, err := h.Routing.ListForDomain(c.Request.Context(), id)
	if err != nil {
		response.Internal(c, err)
		return
	}
	response.OK(c, gin.H{"routing_rules": out})
}

// parseID parses /:id as int64 and writes a 400 on parse failure.
// Returns (0, false) and aborts when the param is malformed.
func parseID(c *gin.Context) (int64, bool) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		response.BadRequest(c, errors.New("invalid id"))
		return 0, false
	}
	return id, true
}

// ── Response-Header CRUD ──────────────────────────────────────────────
//
// Header werden über `http-response set-header` von HAProxy gesetzt
// (siehe internal/haproxy/haproxy.cfg.tpl). Name ist case-insensitive
// unique pro Domain — Doppel-Eintrag erkennt PG selbst via Unique-Index
// und liefert 409 zurück.

func (h *DomainsHandler) ListHeaders(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}
	out, err := h.Headers.ListForDomain(c.Request.Context(), id)
	if err != nil {
		response.Internal(c, err)
		return
	}
	response.OK(c, gin.H{"headers": out})
}

func (h *DomainsHandler) CreateHeader(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}
	var req models.DomainResponseHeader
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err)
		return
	}
	req.DomainID = id
	if !validHeaderName(req.Name) {
		response.BadRequest(c, errors.New("invalid header name"))
		return
	}
	out, err := h.Headers.Create(c.Request.Context(), req)
	if err != nil {
		response.Internal(c, err)
		return
	}
	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "domain.header.create", out.Name, out, h.NodeID)
	response.Created(c, out); h.reload(c.Request.Context(), "header.create")
}

func (h *DomainsHandler) UpdateHeader(c *gin.Context) {
	_, ok := parseID(c)
	if !ok {
		return
	}
	hid, err := strconv.ParseInt(c.Param("hid"), 10, 64)
	if err != nil {
		response.BadRequest(c, errors.New("invalid header id"))
		return
	}
	var req models.DomainResponseHeader
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err)
		return
	}
	if !validHeaderName(req.Name) {
		response.BadRequest(c, errors.New("invalid header name"))
		return
	}
	out, err := h.Headers.Update(c.Request.Context(), hid, req)
	if err != nil {
		if errors.Is(err, domainheaders.ErrNotFound) {
			response.NotFound(c, err)
			return
		}
		response.Internal(c, err)
		return
	}
	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "domain.header.update", out.Name, out, h.NodeID)
	response.OK(c, out); h.reload(c.Request.Context(), "header.update")
}

func (h *DomainsHandler) DeleteHeader(c *gin.Context) {
	_, ok := parseID(c)
	if !ok {
		return
	}
	hid, err := strconv.ParseInt(c.Param("hid"), 10, 64)
	if err != nil {
		response.BadRequest(c, errors.New("invalid header id"))
		return
	}
	if err := h.Headers.Delete(c.Request.Context(), hid); err != nil {
		if errors.Is(err, domainheaders.ErrNotFound) {
			response.NotFound(c, err)
			return
		}
		response.Internal(c, err)
		return
	}
	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "domain.header.delete",
		strconv.FormatInt(hid, 10), gin.H{"id": hid}, h.NodeID)
	response.NoContent(c); h.reload(c.Request.Context(), "header.delete")
}

// validHeaderName: RFC 7230 token chars. Wir engen das auf eine
// vernünftige Untermenge ein (a-z A-Z 0-9 + `-`), damit niemand
// versehentlich Newlines oder Quotes in den HAProxy-Renderer schiebt
// und die Config-Datei sprengt.
func validHeaderName(name string) bool {
	if name == "" || len(name) > 100 {
		return false
	}
	for _, r := range name {
		switch {
		case r >= 'a' && r <= 'z',
			r >= 'A' && r <= 'Z',
			r >= '0' && r <= '9',
			r == '-':
			// ok
		default:
			return false
		}
	}
	return true
}

func actorOf(c *gin.Context) string {
	if t := CurrentToken(c); t != nil {
		return t.Actor
	}
	return "unknown"
}