package main

import (
	"net/http"
	"strings"

	"fn-registry/functions/infra"
)

const maxBodyBytes = 1 << 20 // 1 MiB

func badRequest(w http.ResponseWriter, msg string) {
	infra.HTTPErrorResponse(w, infra.HTTPError{Status: http.StatusBadRequest, Code: "bad_request", Message: msg})
}

func notFound(w http.ResponseWriter, msg string) {
	infra.HTTPErrorResponse(w, infra.HTTPError{Status: http.StatusNotFound, Code: "not_found", Message: msg})
}

func serverError(w http.ResponseWriter, err error) {
	infra.HTTPErrorResponse(w, infra.HTTPError{Status: http.StatusInternalServerError, Code: "internal", Message: err.Error()})
}

// GET /api/board → { columns: [...], cards: [...] }
func handleGetBoard(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		cols, err := db.ListColumns()
		if err != nil {
			serverError(w, err)
			return
		}
		cards, err := db.ListCardsWithTime()
		if err != nil {
			serverError(w, err)
			return
		}
		infra.HTTPJSONResponse(w, http.StatusOK, map[string]any{
			"columns": cols,
			"cards":   cards,
		})
	}
}

// POST /api/columns { name }
func handleCreateColumn(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var body struct{ Name string `json:"name"` }
		if err := infra.HTTPParseBody(r, &body, maxBodyBytes); err != nil {
			badRequest(w, err.Error())
			return
		}
		if strings.TrimSpace(body.Name) == "" {
			badRequest(w, "name required")
			return
		}
		c, err := db.CreateColumn(body.Name)
		if err != nil {
			serverError(w, err)
			return
		}
		infra.HTTPJSONResponse(w, http.StatusCreated, c)
	}
}

// PATCH /api/columns/{id} { name?, position?, location?, width? }
func handleUpdateColumn(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := r.PathValue("id")
		var body struct {
			Name     *string `json:"name"`
			Position *int    `json:"position"`
			Location *string `json:"location"`
			Width    *int    `json:"width"`
		}
		if err := infra.HTTPParseBody(r, &body, maxBodyBytes); err != nil {
			badRequest(w, err.Error())
			return
		}
		if err := db.UpdateColumn(id, ColumnPatch{Name: body.Name, Position: body.Position, Location: body.Location, Width: body.Width}); err != nil {
			serverError(w, err)
			return
		}
		w.WriteHeader(http.StatusNoContent)
	}
}

// DELETE /api/columns/{id}
func handleDeleteColumn(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := r.PathValue("id")
		if err := db.DeleteColumn(id); err != nil {
			serverError(w, err)
			return
		}
		w.WriteHeader(http.StatusNoContent)
	}
}

// POST /api/columns/reorder { ids: [...] }
func handleReorderColumns(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var body struct{ IDs []string `json:"ids"` }
		if err := infra.HTTPParseBody(r, &body, maxBodyBytes); err != nil {
			badRequest(w, err.Error())
			return
		}
		if err := db.ReorderColumns(body.IDs); err != nil {
			serverError(w, err)
			return
		}
		w.WriteHeader(http.StatusNoContent)
	}
}

// POST /api/cards { column_id, requester?, title, description? }
func handleCreateCard(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var body struct {
			ColumnID    string `json:"column_id"`
			Requester   string `json:"requester"`
			Title       string `json:"title"`
			Description string `json:"description"`
		}
		if err := infra.HTTPParseBody(r, &body, maxBodyBytes); err != nil {
			badRequest(w, err.Error())
			return
		}
		if body.ColumnID == "" || strings.TrimSpace(body.Title) == "" {
			badRequest(w, "column_id and title required")
			return
		}
		c, err := db.CreateCard(body.ColumnID, body.Requester, body.Title, body.Description)
		if err != nil {
			serverError(w, err)
			return
		}
		infra.HTTPJSONResponse(w, http.StatusCreated, c)
	}
}

// PATCH /api/cards/{id} { requester?, title?, description?, color? }
func handleUpdateCard(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := r.PathValue("id")
		var body struct {
			Requester   *string `json:"requester"`
			Title       *string `json:"title"`
			Description *string `json:"description"`
			Color       *string `json:"color"`
		}
		if err := infra.HTTPParseBody(r, &body, maxBodyBytes); err != nil {
			badRequest(w, err.Error())
			return
		}
		if err := db.UpdateCard(id, CardPatch{Requester: body.Requester, Title: body.Title, Description: body.Description, Color: body.Color}); err != nil {
			serverError(w, err)
			return
		}
		w.WriteHeader(http.StatusNoContent)
	}
}

// DELETE /api/cards/{id}
func handleDeleteCard(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := r.PathValue("id")
		if err := db.DeleteCard(id); err != nil {
			serverError(w, err)
			return
		}
		w.WriteHeader(http.StatusNoContent)
	}
}

// POST /api/cards/{id}/move { column_id, ordered_ids }
func handleMoveCard(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := r.PathValue("id")
		var body struct {
			ColumnID   string   `json:"column_id"`
			OrderedIDs []string `json:"ordered_ids"`
		}
		if err := infra.HTTPParseBody(r, &body, maxBodyBytes); err != nil {
			badRequest(w, err.Error())
			return
		}
		if body.ColumnID == "" {
			badRequest(w, "column_id required")
			return
		}
		if err := db.MoveCard(id, body.ColumnID, body.OrderedIDs); err != nil {
			if strings.Contains(err.Error(), "not found") {
				notFound(w, "card not found")
				return
			}
			serverError(w, err)
			return
		}
		w.WriteHeader(http.StatusNoContent)
	}
}

// GET /api/cards/{id}/history → [HistoryEntry, ...]
func handleCardHistory(db *DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id := r.PathValue("id")
		entries, err := db.CardHistory(id)
		if err != nil {
			serverError(w, err)
			return
		}
		infra.HTTPJSONResponse(w, http.StatusOK, entries)
	}
}

func apiRoutes(db *DB, chatWorkdir string, logger *ChatLogger) []infra.Route {
	return []infra.Route{
		{Method: "GET", Path: "/api/board", Handler: handleGetBoard(db)},
		{Method: "POST", Path: "/api/columns", Handler: handleCreateColumn(db)},
		{Method: "POST", Path: "/api/columns/reorder", Handler: handleReorderColumns(db)},
		{Method: "PATCH", Path: "/api/columns/{id}", Handler: handleUpdateColumn(db)},
		{Method: "DELETE", Path: "/api/columns/{id}", Handler: handleDeleteColumn(db)},
		{Method: "POST", Path: "/api/cards", Handler: handleCreateCard(db)},
		{Method: "PATCH", Path: "/api/cards/{id}", Handler: handleUpdateCard(db)},
		{Method: "DELETE", Path: "/api/cards/{id}", Handler: handleDeleteCard(db)},
		{Method: "POST", Path: "/api/cards/{id}/move", Handler: handleMoveCard(db)},
		{Method: "GET", Path: "/api/cards/{id}/history", Handler: handleCardHistory(db)},
		{Method: "POST", Path: "/api/chat", Handler: handleChat(db, chatWorkdir, logger)},
	}
}