package api

import (
	"net/http"
	"strconv"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/lerko/nib/internal/db"
)

type CreateEntityRequest struct {
	Body        string   `json:"body"`
	Title       *string  `json:"title"`
	Description *string  `json:"description"`
	Glyph       *string  `json:"glyph"`
	TimeAnchor  *string  `json:"time_anchor"`
	Tags        []string `json:"tags"`
	CardType    *string  `json:"card_type"`
	CardData    *string  `json:"card_data"`
}

type UpdateEntityRequest struct {
	Body        *string   `json:"body"`
	Title       *string   `json:"title"`
	Description *string   `json:"description"`
	Glyph       *string   `json:"glyph"`
	TimeAnchor  *string   `json:"time_anchor"`
	Tags        *[]string `json:"tags"`
	Pinned      *bool     `json:"pinned"`
	CardType    *string   `json:"card_type"`
	CardData    *string   `json:"card_data"`
}

type PromoteRequest struct {
	CardType string  `json:"card_type"`
	CardData *string `json:"card_data"`
}

func listEntities(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		p := db.DefaultListParams()

		if tag := r.URL.Query().Get("tag"); tag != "" {
			p.Tag = &tag
		}
		if date := r.URL.Query().Get("date"); date != "" {
			if _, err := time.Parse("2006-01-02", date); err != nil {
				writeError(w, http.StatusBadRequest, "invalid_input", "bad date format, use YYYY-MM-DD")
				return
			}
			p.Date = &date
		}
		if from := r.URL.Query().Get("from"); from != "" {
			if _, err := time.Parse("2006-01-02", from); err != nil {
				writeError(w, http.StatusBadRequest, "invalid_input", "bad from format, use YYYY-MM-DD")
				return
			}
			p.From = &from
		}
		if to := r.URL.Query().Get("to"); to != "" {
			if _, err := time.Parse("2006-01-02", to); err != nil {
				writeError(w, http.StatusBadRequest, "invalid_input", "bad to format, use YYYY-MM-DD")
				return
			}
			p.To = &to
		}
		if r.URL.Query().Get("cards_only") == "true" {
			p.CardsOnly = true
		}
		if r.URL.Query().Get("include_deleted") == "true" {
			p.IncludeDeleted = true
		}
		if sort := r.URL.Query().Get("sort"); sort != "" {
			if sort != "created" && sort != "use_count" {
				writeError(w, http.StatusBadRequest, "invalid_input", "sort must be 'created' or 'use_count'")
				return
			}
			p.Sort = sort
		}
		if order := r.URL.Query().Get("order"); order != "" {
			if order != "asc" && order != "desc" {
				writeError(w, http.StatusBadRequest, "invalid_input", "order must be 'asc' or 'desc'")
				return
			}
			p.Order = order
		}
		if limitStr := r.URL.Query().Get("limit"); limitStr != "" {
			limit, err := strconv.Atoi(limitStr)
			if err != nil || limit < 1 {
				writeError(w, http.StatusBadRequest, "invalid_input", "limit must be a positive integer")
				return
			}
			p.Limit = limit
		}
		if offsetStr := r.URL.Query().Get("offset"); offsetStr != "" {
			offset, err := strconv.Atoi(offsetStr)
			if err != nil || offset < 0 {
				writeError(w, http.StatusBadRequest, "invalid_input", "offset must be a non-negative integer")
				return
			}
			p.Offset = offset
		}

		entities, err := store.List(p)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}

		resp := make([]EntityResponse, len(entities))
		for i, e := range entities {
			resp[i] = entityToResponse(e)
		}
		writeJSON(w, http.StatusOK, resp)
	}
}

func createEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var req CreateEntityRequest
		if !decodeJSON(w, r, &req) {
			return
		}

		if req.Body == "" && req.Title == nil {
			writeError(w, http.StatusBadRequest, "invalid_input", "body or title is required")
			return
		}

		glyph := db.GlyphNote
		if req.Glyph != nil {
			if !db.ValidGlyph(*req.Glyph) {
				writeError(w, http.StatusBadRequest, "invalid_input", "invalid glyph value")
				return
			}
			glyph = db.Glyph(*req.Glyph)
		}

		e := &db.Entity{
			Body:        req.Body,
			Title:       req.Title,
			Description: req.Description,
			Glyph:       glyph,
			TimeAnchor:  req.TimeAnchor,
			Tags:        req.Tags,
		}

		if req.CardType != nil {
			if !db.ValidCardType(*req.CardType) {
				writeError(w, http.StatusBadRequest, "invalid_type", "invalid card_type value")
				return
			}
			ct := db.CardType(*req.CardType)
			e.CardType = &ct
			e.CardData = req.CardData
		}

		if err := store.Create(e); err != nil {
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}

		writeJSON(w, http.StatusCreated, entityToResponse(e))
	}
}

func getEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")
		e, err := store.Get(id)
		if err != nil {
			if err == db.ErrNotFound {
				writeError(w, http.StatusNotFound, "not_found", "no entity with id "+id)
				return
			}
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}
		writeJSON(w, http.StatusOK, entityToResponse(e))
	}
}

func updateEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")

		var req UpdateEntityRequest
		if !decodeJSON(w, r, &req) {
			return
		}

		u := &db.EntityUpdate{}
		u.Body = req.Body
		u.Title = req.Title
		u.Description = req.Description
		u.Tags = req.Tags
		u.Pinned = req.Pinned
		u.CardData = req.CardData

		if req.Glyph != nil {
			if !db.ValidGlyph(*req.Glyph) {
				writeError(w, http.StatusBadRequest, "invalid_input", "invalid glyph value")
				return
			}
			g := db.Glyph(*req.Glyph)
			u.Glyph = &g
		}
		if req.TimeAnchor != nil {
			u.TimeAnchor = req.TimeAnchor
		}
		if req.CardType != nil {
			if !db.ValidCardType(*req.CardType) {
				writeError(w, http.StatusBadRequest, "invalid_type", "invalid card_type value")
				return
			}
			ct := db.CardType(*req.CardType)
			u.CardType = &ct
		}

		if err := store.Update(id, u); err != nil {
			if err == db.ErrNotFound {
				writeError(w, http.StatusNotFound, "not_found", "no entity with id "+id)
				return
			}
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}

		e, err := store.Get(id)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}
		writeJSON(w, http.StatusOK, entityToResponse(e))
	}
}

type DeleteResponse struct {
	Result string `json:"result"`
}

func deleteEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")
		result, err := store.SoftDelete(id)
		if err != nil {
			if err == db.ErrNotFound {
				writeError(w, http.StatusNotFound, "not_found", "no entity with id "+id)
				return
			}
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}
		label := "soft"
		if result == db.DeletedHard {
			label = "hard"
		}
		writeJSON(w, http.StatusOK, DeleteResponse{Result: label})
	}
}

func promoteEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")

		var req PromoteRequest
		if !decodeJSON(w, r, &req) {
			return
		}

		if req.CardType == "" {
			writeError(w, http.StatusBadRequest, "invalid_input", "card_type is required")
			return
		}
		if !db.ValidCardType(req.CardType) {
			writeError(w, http.StatusBadRequest, "invalid_type", "invalid card_type value")
			return
		}

		if err := store.Promote(id, db.CardType(req.CardType), req.CardData); err != nil {
			if err == db.ErrNotFound {
				writeError(w, http.StatusNotFound, "not_found", "no entity with id "+id)
				return
			}
			if err == db.ErrAlreadyPromoted {
				writeError(w, http.StatusBadRequest, "invalid_promote", "entity is already crystallized")
				return
			}
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}

		e, err := store.Get(id)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}
		writeJSON(w, http.StatusOK, entityToResponse(e))
	}
}

func demoteEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")

		if err := store.Demote(id); err != nil {
			if err == db.ErrNotFound {
				writeError(w, http.StatusNotFound, "not_found", "no entity with id "+id)
				return
			}
			if err == db.ErrAlreadyFluid {
				writeError(w, http.StatusBadRequest, "invalid_demote", "entity is already fluid")
				return
			}
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}

		e, err := store.Get(id)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}
		writeJSON(w, http.StatusOK, entityToResponse(e))
	}
}

type AbsorbRequest struct {
	SourceID string `json:"source_id"`
}

func absorbEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")

		var req AbsorbRequest
		if !decodeJSON(w, r, &req) {
			return
		}

		if req.SourceID == "" {
			writeError(w, http.StatusBadRequest, "invalid_input", "source_id is required")
			return
		}
		if req.SourceID == id {
			writeError(w, http.StatusBadRequest, "invalid_input", "target and source must be different entities")
			return
		}

		if err := store.Absorb(id, req.SourceID); err != nil {
			if err == db.ErrNotFound {
				writeError(w, http.StatusNotFound, "not_found", "target or source entity not found")
				return
			}
			if err == db.ErrTargetCrystallized {
				writeError(w, http.StatusBadRequest, "invalid_absorb", "target is crystallized — demote first")
				return
			}
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}

		e, err := store.Get(id)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}
		writeJSON(w, http.StatusOK, entityToResponse(e))
	}
}

func useEntity(store *db.Store) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")

		if err := store.IncrementUse(id); err != nil {
			if err == db.ErrNotFound {
				writeError(w, http.StatusNotFound, "not_found", "no entity with id "+id)
				return
			}
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}

		e, err := store.Get(id)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
			return
		}
		writeJSON(w, http.StatusOK, entityToResponse(e))
	}
}